SNOW-2111927: fix thread handle leak from event loop

[sfc-gh-ext-simba-hx]

teamwork issue 1265
The handle leak is from event loop having a duplicated thread handle opened in thread itself.

[Copilot]

Pull Request Overview

This PR addresses a handle leak in the EventLoopGroup by ensuring threads are managed rather than detached.

• Sets the thread join strategy to AWS_TJS_MANAGED to allow proper cleanup.
• Adds a comment indicating the change for SNOW-2111927.

Comments suppressed due to low confidence (1)

crt/aws-crt-cpp/crt/aws-c-io/source/event_loop.c:124

• Add or update a unit test to verify that using AWS_TJS_MANAGED indeed prevents thread handle leaks when the event loop group is shut down.

            thread_options.join_strategy = AWS_TJS_MANAGED;

[sfc-gh-dstempniak]

LGTM

[sfc-gh-ext-simba-hx]

Hi @sfc-gh-dstempniak @sfc-gh-jszczerbinski
I'm not authorized to push to branch deps/aws-sdk-1.11.283 so can't merge this PR.
Please go ahead to merge it once you think it's all good.
On the other hand, in the PR for updating aws sdk I'll download the source from original repo and apply a patch which would be made from all custom changes in deps/aws-sdk-1.11.283 branch.