Constrain SSM TriggerType parameter to allowlisted values

[sgmenda]

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.

[github-actions]

🔒 Security Review — View Report

Please review before merging.

[nhatnghiho]

This is dead code in our repo. Good to close!

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.50%. Comparing base (f3e723d) to head (7e8117c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3672      +/-   ##
==========================================
- Coverage   78.70%   78.50%   -0.20%     
==========================================
  Files         705      705              
  Lines      130758   130755       -3     
  Branches    17921    17917       -4     
==========================================
- Hits       102914   102652     -262     
- Misses      26864    27127     +263     
+ Partials      980      976       -4     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.