THRIFT-5297: Improve TThreadPoolServer Handling of Incoming Connections

[belugabehr]

• Did you create an Apache Jira ticket? (not required for trivial changes)
• If a ticket exists: Does your pull request title follow the pattern "THRIFT-NNNN: describe my issue"?
• [x ] Did you squash your changes to a single commit? (not required, but preferred)
• Did you do your best to avoid breaking changes? If one was needed, did you label the Jira ticket with "Breaking-Change"?
• If your change does not involve any code, include [skip ci] anywhere in the commit message to free up build resources.

[Jens-G]

@belugabehr There seem no objections from anyone. What about triggering the CI again and commit if all is green?
@ java devs: Any comments on this change?

[belugabehr]

@Jens-G Thank you for your interest. I believe there were some comment about moving the back-off functionality to the client code, which is not inappropriate, but I have not yet had the time to implement.

Happy to get this part in first if that's OK.

[belugabehr]

@Jens-G Any ideas on how to kick off the automated build/test suite?

[belugabehr]

OK. Looks like there was a lag. All good now.

I ran into some hardship recently trying to debug an application build on Thrift server. I have some ideas for making it more debug-able, but need this in first and then can build on it.

[belugabehr]

@Jens-G Should be good to go now. C++ failures only.