Beam 3984 - adding a unit test to verify that Initialize prevents traffic in C#MS

[cdhanna]

Ticket

https://disruptorbeam.atlassian.net/browse/BEAM-3984

Brief Description

We have a report that if you do async work in an InitializeServices method in a C#MS, it won't prevent traffic from appearing; but that is false. We do wait, and this test helps verify that truth.

Checklist

• Have you added appropriate text to the CHANGELOG.md files?

Add those to list or remove the list below altogether:

• Have you documented all your public methods and interfaces? Have you identified intention and assumptions?
• Have you included a docs file as /wiki/BEAM-1234.md? You need to provide a docs file.

Notes

When you are merging a feature branch into main, please squash merge and make sure the final commit contains any relevent JIRA ticket number. If you are merging from main to staging, or staging to production, please use a regular merge commit.

Does this introduce tech-debt? If so, have you added an entry to the Tech-debt document?

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