Bug 1990559 [wpt PR 55044] - Refactor the interestfor-invoker-descendants.tentative.html test, a=testonly

Automatic update from web-platform-tests
Refactor the interestfor-invoker-descendants.tentative.html test

Just cleans it up - no functional change.

Bug: 326681249
Change-Id: I8dad148ad76743befd8725b9dfeb0a25a5e5e489
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6974990
Reviewed-by: Joey Arhar <jarharchromium.org>
Commit-Queue: Mason Freed <masonfchromium.org>
Cr-Commit-Position: refs/heads/main{#1520344}

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wpt-commits: 62b62702ef7ef2e2c10494e62eee5435fbfa37a4
wpt-pr: 55044

UltraBlame original commit: 5202e38aeb52fbf1ebd180afba144ce6ee33753a

Author: marco-c