Count VPN controller cancellations (#2720)

Task/Issue URL:
https://app.asana.com/0/1199230911884351/1207193126056882/f

## Description

Stop counting when the user disables the VPN configuration creation as a
controller start failure.

DuckDuckGo/NetworkProtection/AppAndExtensionAndAgentTargets/NetworkProtectionPixelEvent.swift

@@ -28,6 +28,7 @@ enum NetworkProtectionPixelEvent: PixelKitEventV2 {
 
     case networkProtectionControllerStartAttempt
     case networkProtectionControllerStartSuccess
+    case networkProtectionControllerStartCancelled
     case networkProtectionControllerStartFailure(_ error: Error)
 
     case networkProtectionTunnelStartAttempt
@@ -122,6 +123,9 @@ enum NetworkProtectionPixelEvent: PixelKitEventV2 {
         case .networkProtectionControllerStartSuccess:
             return "netp_controller_start_success"
 
+        case .networkProtectionControllerStartCancelled:
+            return "netp_controller_start_cancelled"
+
         case .networkProtectionControllerStartFailure:
             return "netp_controller_start_failure"
 
@@ -344,6 +348,7 @@ enum NetworkProtectionPixelEvent: PixelKitEventV2 {
                 .networkProtectionNewUser,
                 .networkProtectionControllerStartAttempt,
                 .networkProtectionControllerStartSuccess,
+                .networkProtectionControllerStartCancelled,
                 .networkProtectionControllerStartFailure,
                 .networkProtectionTunnelStartAttempt,
                 .networkProtectionTunnelStartSuccess,
@@ -415,6 +420,7 @@ enum NetworkProtectionPixelEvent: PixelKitEventV2 {
                 .networkProtectionNewUser,
                 .networkProtectionControllerStartAttempt,
                 .networkProtectionControllerStartSuccess,
+                .networkProtectionControllerStartCancelled,
                 .networkProtectionTunnelStartAttempt,
                 .networkProtectionTunnelStartSuccess,
                 .networkProtectionTunnelStopAttempt,

DuckDuckGo/NetworkProtection/AppTargets/BothAppTargets/NetworkProtectionTunnelController.swift

@@ -448,14 +448,18 @@ final class NetworkProtectionTunnelController: TunnelController, TunnelSessionPr
 
     // MARK: - Starting & Stopping the VPN
 
-    enum StartError: LocalizedError {
+    enum StartError: LocalizedError, CustomNSError {
+        case cancelled
         case noAuthToken
         case connectionStatusInvalid
         case connectionAlreadyStarted
         case simulateControllerFailureError
+        case startTunnelFailure(_ error: Error)
 
         var errorDescription: String? {
             switch self {
+            case .cancelled:
+                return nil
             case .noAuthToken:
                 return "You need a subscription to start the VPN"
             case .connectionAlreadyStarted:
@@ -473,6 +477,34 @@ final class NetworkProtectionTunnelController: TunnelController, TunnelSessionPr
 #endif
             case .simulateControllerFailureError:
                 return "Simulated a controller error as requested"
+            case .startTunnelFailure(let error):
+                return error.localizedDescription
+            }
+        }
+
+        var errorCode: Int {
+            switch self {
+            case .cancelled: return 0
+                // MARK: Setup errors
+            case .noAuthToken: return 1
+            case .connectionStatusInvalid: return 2
+            case .connectionAlreadyStarted: return 3
+            case .simulateControllerFailureError: return 4
+                // MARK: Actual connection attempt issues
+            case .startTunnelFailure: return 100
+            }
+        }
+
+        var errorUserInfo: [String: Any] {
+            switch self {
+            case .cancelled,
+                    .noAuthToken,
+                    .connectionStatusInvalid,
+                    .connectionAlreadyStarted,
+                    .simulateControllerFailureError:
+                return [:]
+            case .startTunnelFailure(let error):
+                return [NSUnderlyingErrorKey: error]
             }
         }
     }
@@ -502,6 +534,8 @@ final class NetworkProtectionTunnelController: TunnelController, TunnelSessionPr
             } catch {
                 if case NEVPNError.configurationReadWriteFailed = error {
                     onboardingStatusRawValue = OnboardingStatus.isOnboarding(step: .userNeedsToAllowVPNConfiguration).rawValue
+
+                    throw StartError.cancelled
                 }
 
                 throw error
@@ -528,9 +562,15 @@ final class NetworkProtectionTunnelController: TunnelController, TunnelSessionPr
         } catch {
             VPNOperationErrorRecorder().recordControllerStartFailure(error)
 
-            PixelKit.fire(
-                NetworkProtectionPixelEvent.networkProtectionControllerStartFailure(error), frequency: .dailyAndCount, includeAppVersionParameter: true
-            )
+            if case StartError.cancelled = error {
+                PixelKit.fire(
+                    NetworkProtectionPixelEvent.networkProtectionControllerStartCancelled, frequency: .dailyAndCount, includeAppVersionParameter: true
+                )
+            } else {
+                PixelKit.fire(
+                    NetworkProtectionPixelEvent.networkProtectionControllerStartFailure(error), frequency: .dailyAndCount, includeAppVersionParameter: true
+                )
+            }
 
             await stop()
 
@@ -577,7 +617,11 @@ final class NetworkProtectionTunnelController: TunnelController, TunnelSessionPr
             throw StartError.simulateControllerFailureError
         }
 
-        try tunnelManager.connection.startVPNTunnel(options: options)
+        do {
+            try tunnelManager.connection.startVPNTunnel(options: options)
+        } catch {
+            throw StartError.startTunnelFailure(error)
+        }
 
         PixelKit.fire(
             NetworkProtectionPixelEvent.networkProtectionNewUser,