CI: Do not run build-plugin-zip when PR metadata changes

[yogeshbhutkar]

What, Why, and How?

While working on other PRs, I noticed that build-plugin-zip reruns for PR metadata-only changes, such as title or description edits. Each run takes about three minutes, and since the generated artifact depends on the PR code rather than PR metadata, repeated edits can waste CI time. This change limits the workflow to code-relevant PR events (opened, synchronize, and reopened), matching Gutenberg’s corresponding workflow, which uses the default pull_request activity types.

P.S. edited also runs when the PR base branch changes. If we decide that base-branch changes should still rebuild the plugin ZIP (which I don't think is required), we can keep edited and add an if guard so only that specific edit path triggers the workflow.

Use of AI Tools

AI assistance: Yes
Tool(s): Codex
Model(s): GPT-5.5
Used for: Code review

Testing Instructions

• CI should be green.
• Changing PR metadata should not trigger build-plugin-zip.

Changelog Entry

Fixed - Prevent unnecessary plugin ZIP rebuilds when a pull request metadata is edited

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.50%. Comparing base (30fc728) to head (a5bcb0e).

Additional details and impacted files

@@            Coverage Diff             @@
##             develop     #841   +/-   ##
==========================================
  Coverage      75.50%   75.50%           
  Complexity      2086     2086           
==========================================
  Files             99       99           
  Lines           8626     8626           
==========================================
  Hits            6513     6513           
  Misses          2113     2113           

Flag	Coverage Δ
unit	75.50% <ø> (ø)

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[github-actions]

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[dkotter]

I'm open to thoughts here but this workflow is intentionally run on the edited flow as the purpose of this workflow is to build a final plugin zip which then triggers our PR Playground Preview workflow.

That workflow will add a link to the PR description that will open that PR in a Playground instance. That workflow uses the WordPress Playground PR Preview Action and it recommends using the edited action. The main reason for that is if someone edits the PR and removes the Playground link, the workflow will automatically trigger and add it back.

[yogeshbhutkar]

This makes sense to me. Thank you for your time. Closing this PR as this is a calculated decision.