Re-Enable RuntimeEventSource test.

[jorive]

The test is unnecessarily flaky and unreliable.
It needs to be improved and re-enabled.

[vancem]

Was disabled with PR dotnet/coreclr#22899. Because of failures: #10677, #10848, #11989, #12082.

[tommcdon]

Related to https://github.com/dotnet/coreclr/issues/23124 in that the test is relying on the same bad behavior of counting events and assuming the the number of events is the same