fix cancel s3crt request callback to not outlive request lifetime

[sbiscigl]

Issue #, if available:

#3639

Description of changes:

there is a problem with the method CancelCrtRequestAsync. In that method we use the sdk thread executor to spin up a cancel request

m_clientConfiguration.executor->Submit([meta_request]() { aws_s3_meta_request_cancel(meta_request); });

if the request finished before that cleanup request can be processed the cleanup with segfault.

Check all that applies:

• Did a review by yourself.
• Added proper tests to cover this PR. (If tests are not applicable, explain.)
• Checked if this PR is a breaking (APIs have been changed) change.
• Checked if this PR will not introduce cross-platform inconsistent behavior.
• Checked if this PR would require a ReadMe/Wiki update.

Check which platforms you have built SDK on to verify the correctness of this PR.

• Linux
• Windows
• Android
• MacOS
• IOS
• Other Platforms

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.