test scripts break when a folder with snips is created and removed in the same PR #15200
Description
In #15168 we created ambient/getting-started/setup/snips.sh, and it was removed in a later commit.
Now, tests won't pass, because scripts/pr_tests.pyis looking at all the places a snips.sh existed in all commits, not just in the end state.
+ echo 'Optimizing tests for pull number: 15168'
Optimizing tests for pull number: 15168
++ python3 ./scripts/pr_tests.py --token= 15168
+ TESTS=ambient/usage/extend-waypoint-wasm,ambient/getting-started/setup,ambient/getting-started/cleanup,ambient/getting-started/manage-traffic,ambient/getting-started/secure-and-visualize,ambient/getting-started/enforce-auth-policies,ambient/getting-started/deploy-sample-app,ambient/getting-started