test: fix API integration getAll list elements

[lawmicha]

Issue #

Description

The test was incorrectly aggregating the results from the list instance. The test will fail if the results came back on the first fetch call as it was getting dropped

AWSAPIPluginFunctionalTests.GraphQLConnectionScenario6Tests
  testGetBlogThenFetchPostsThenFetchComments, XCTAssertEqual failed: ("0") is not equal to ("2")
  /Users/runner/work/amplify-swift/amplify-swift/AmplifyPlugins/API/Tests/APIHostApp/AWSAPIPluginFunctionalTests/GraphQLConnectionScenario6Tests.swift:99

    let allPosts = try await getAll(list: resultPosts)
    XCTAssertEqual(allPosts.count, 2)
    guard let fetchedPost = allPosts.first(where: { (post) -> Bool in

testGetBlogThenFetchPostsThenFetchComments, failed - Could not set up - failed to get a post and its comments
/Users/runner/work/amplify-swift/amplify-swift/AmplifyPlugins/API/Tests/APIHostApp/AWSAPIPluginFunctionalTests/GraphQLConnectionScenario6Tests.swift:103

    }), let comments = fetchedPost.comments else {
        XCTFail("Could not set up - failed to get a post and its comments")
        return

   Executed 67 tests, with 2 failures (0 unexpected) in 91.169 (91.202) seconds

General Checklist

• Added new tests to cover change, if needed
• Build succeeds with all target using Swift Package Manager
• All unit tests pass
• All integration tests pass
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• Documentation update for the change if required
• PR title conforms to conventional commit style
• New or updated tests include Given When Then inline code documentation and are named accordingly testThing_condition_expectation()
• If breaking change, documentation/changelog update with migration instructions

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.