Fix integer increment race condition

[JamesNK]

Description

Seen in EventsCanBePublishedNonBlockingConcurrent test results:

Assert.Equal() Failure: Values differ
Expected: 2
Actual:   1

It looks like events with code hitCount++ are run conccurent so the test will break if incremented at the same time. Use thread-safe increment.

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No
• Does the change require an update in our Aspire docs?
  • Yes
    • Link to aspire-docs issue:
  • No

Microsoft Reviewers: Open in CodeFlow

[JamesNK]

I found more cases of integers incremented inside events and callbacks. I think many of these aren't a problem, but there isn't harm in using the thread safe way to increment value in potentially multithreaded code.