aws-custom-route-controller ControlPlane health checks are failing because Event that is already resolved

[ialidzhikov]

How to categorize this issue?

/area quality
/kind bug
/platform aws

What happened:
#688 introduced the following health check - it checks for events created by aws-route-controller and fails the ControlPlane health check when there is event of type Warning.
While this can help with issues that cannot be resolved on its own, this also is leading to a lot of false-positive results:
For example the route-controller failed to updated routes 50mins ago:

53m         Warning   RoutesUpdateFailed             serviceaccount/aws-custom-route-controller   creating route 10.101.10.0/24 -> i-<uid> in table rtb-<uid> failed: IncorrectInstanceState: Instance with state 'shutting-down' is not valid for this operation....
53m         Warning   RoutesUpdateFailed             serviceaccount/aws-custom-route-controller   creating route 10.101.10.0/24 -> i-<uid> in table rtb-<uid> failed: IncorrectInstanceState: Instance with state 'shutting-down' is not valid for this operation....
53m         Warning   RoutesUpdateFailed             serviceaccount/aws-custom-route-controller   creating route 10.101.10.0/24 -> i-<uid> in table rtb-<uid> failed: InvalidParameterValue: Invalid value 'i-<uid>' for instance ID. Instance is not in a VPC....
52m         Warning   RoutesUpdateFailed             serviceaccount/aws-custom-route-controller   creating route 10.101.10.0/24 -> i-<uid> in table rtb-<uid> failed: InvalidParameterValue: Invalid value 'i-<uid>' for instance ID. Instance is not in a VPC....
52m         Warning   RoutesUpdateFailed             serviceaccount/aws-custom-route-controller   creating route 10.101.10.0/24 -> i-<uid> in table rtb-<uid> failed: InvalidParameterValue: Invalid value 'i-<uid>' for instance ID. Instance is not in a VPC....

This issue was only temporary one and was fixed on its own. But according to the health check logic, provider-aws will fail the ControlPlane health check until the event is gone from the system. So there was a transient failure for a moment, it resolved on its own, but the health check implementation fails the ControlPlane health check when there is no actual issue.

What you expected to happen:
provider-aws to do not fail the ControlPlane health check with such false-positive results.

How to reproduce it (as minimally and precisely as possible):
See above.

Anything else we need to know?:

Environment:

• Gardener version (if relevant):
• Extension version: v1.42.2
• Kubernetes version (use kubectl version):
• Cloud provider or hardware configuration:
• Others: