tests,misc: Remove edited from PR Action trigger list (#1654)

`edited` is what forces a re-run of our tests when the PR title is
updated and other minor metadata stuff. I believe all changes to the
code are covered by the remainder. `synchronize` is means the PR is
triggered with the when the this PR is from (in this case my forked gem5
repo) is synced with the PR branch here. This covers the vast majority
of cases we care about. `opended` covers for the case where the PR is
created and `ready_for_review` for when something moves out of a draft.

.github/workflows/ci-tests.yaml

@@ -5,7 +5,7 @@ name: CI Tests
 
 on:
     pull_request:
-        types: [opened, edited, synchronize, ready_for_review]
+        types: [opened, synchronize, ready_for_review]
 
 concurrency:
     group: ${{ github.workflow }}-${{ github.ref || github.run_id }}