Make unit/integ tests more reliable

[normj]

Description of changes:
Work on making the tests more reliable and PR checks succeed without retries. After the PR changes I was able to run the PR checks 5 times in a row with no issues.

Changes:

• Removed the OnCompletedCallback_IsExecuted integ test. The test was relying on making a second invoke to Lambda see if a state variable was set from previous run. There is no way to guarantee the second invokes will go to the same Lambda compute instance. The scenario being tested was checking if the ASP.NET Core OnComplete callbacks are called. But the OnComplete callbacks don't have access to the response stream so there is no way to write something back to the caller to say I was called. Hence the reason the AI generated integ test relied on the second call. The fact that the test did pass when the invokes did go to same Lambda compute environment show the feature does work but we don't want to have this flaky test.
• Renamed the ResponseStreamFactory collection to RuntimeSupportStateCheck and applied it to more tests that are testing RuntimeSupport so they would not run in parallel. RuntimeSupport has logic via statics that assume there is only a single instance running a single invocation. All these unit tests run under a few seconds so I'm not worried about tests not running in parallel
• Updated tests creating LambdaBootstrap to pass in mock environment variable collections to avoid bleeding environment variable between tests.
• Removed the MidstreamError_SetsErrorStateWithExceptionDetails unit test. There were too many issues mock of the runtime api to get the timing a 100% right. The scenario being tested is covered in integ tests.

I also removed the .NET 11 targets from RuntimeSupport and SnapShotRestore because we don't need it for OCI images and it was causing issues building in VS.

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