ci(boto): add wait timeout when testing receiving request

[Yun-Kim]

This PR attempts to fix a flaky botocore test, test_sns_send_message_batch_trace_injection_with_max_message_attributes which has repeatedly been failing due to a message not being received. The fix is to add a wait timeout for the poll request.

Checklist

• Change(s) are motivated and described in the PR description.
• Testing strategy is described if automated tests are not included in the PR.
• Risk is outlined (performance impact, potential for breakage, maintainability, etc).
• Change is maintainable (easy to change, telemetry, documentation).
• Library release note guidelines are followed.
• Documentation is included (in-code, generated user docs, public corp docs).
• PR description includes explicit acknowledgement/acceptance of the performance implications of this PR as reported in the benchmarks PR comment.

Reviewer Checklist

• Title is accurate.
• No unnecessary changes are introduced.
• Description motivates each change.
• Avoids breaking API changes unless absolutely necessary.
• Testing strategy adequately addresses listed risk(s).
• Change is maintainable (easy to change, telemetry, documentation).
• Release note makes sense to a user of the library.
• Reviewer has explicitly acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment.

[pr-commenter]

Benchmarks

Comparing candidate commit e390f8c in PR branch yunkim/fix-flaky-boto with baseline commit 28c7283 in branch 1.x.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 56 cases.