Take the bootstrap sweep off pull requests

[sscarduzio]

The problem

master-bootstrap-tests is a 34-version × 2-env matrix — 68 jobs — and it ran on four triggers:

    if: >
      github.event_name == 'schedule' ||
      github.event_name == 'workflow_dispatch' ||
      (github.event_name == 'push' && github.ref == 'refs/heads/master') ||
      (github.event_name == 'pull_request' && github.base_ref == 'master' && ...)

docs/dev/branching.md case 4 sends every pipeline and workflow change to master. Three such PRs moved there today — #120, #122, #126 — and each one queued its own 68 bootstrap jobs behind itself. On #122 the e2e legs it actually needed had all finished:

completed  🔬 E2E Tests (released plugins)  ×13
completed  🧪 E2E Tests (pre-build plugins)
queued     🚀 Bootstrap Tests               ×68

Approved, no failures, and unmergeable for hours — waiting on a sweep of plugins that were released weeks ago.

The change

One clause removed: the pull-request trigger.

    if: >
      github.event_name == 'schedule' ||
      github.event_name == 'workflow_dispatch' ||
      (github.event_name == 'push' && github.ref == 'refs/heads/master')

Every version in that matrix tests a plugin that is already out, so nothing a pull request changes can change the result. The nightly still sweeps them, a push to master still runs it — that is the moment the released set can actually move — and the manual dispatch is still there when someone wants it.

🤖 Generated with Claude Code

[coutoPL]

The change is clear and simple, but the PR title and description unecessary makes it mysterious and smart.

[coutoPL]

The comment violates @docs/dev/style-code.md

Please check other comments added/changed in the PR.

[sscarduzio]

Superseded by #129 (bootstrap sweep in its own weekly workflow, off pull requests).