Add explicit --include-sdist parameter to update lockfiles workflow command

[kdaily]

Issue #, if available:

#8901 (related PR that updated these files recently)

Description of changes:

The include_sdist parameter has a default of True, but this is not clear in the workflow.

https://github.com/aws/aws-cli/blob/2aaa023ce6720e1e90ba4f8eb6a77c3e833af356/scripts/regenerate-lock-files#L211

Adding an explicit parameter helps clarify the intention of running this workflow to regenerate lockfiles for the source distribution:

• requirements/download-deps/bootstrap-lock.txt
• requirements/download-deps/bootstrap-win-lock.txt
• requirements/download-deps/portable-exe-lock.txt
• requirements/download-deps/portable-exe-win-lock.txt
• requirements/download-deps/system-sandbox-lock.txt
• requirements/download-deps/system-sandbox-win-lock.txt

It does not update these "base" lockfiles:

• requirements-dev-lock.txt
• requirements-test-lock.txt
• requirements-base-lock.txt
• requirements-build-lock.txt
• requirements-docs-lock.txt

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