ci(pr-title): skip the title lint for website submission PRs

[KartikP]

Website plugin submissions can no longer merge in vision.

Cause

• The vision master ruleset (24782890, created 2026-10-09 10:24Z) makes title / conventional-title a required check.
• Website submissions open PRs titled brain-score.org submission (user:N) | (public:B). That title always fails the lint, for example vision#2593, #2594 and #2595 (run).
• The automerge path (check_if_pr_is_automergeable / automerge_plugin-only_prs) never looks at the title, but the ruleset blocks the merge anyway.

Fix
Skip the lint step for PRs from same-repo web_submission_* branches. The required job still runs and reports success, and any stale "title" comment is deleted.

Why exempt instead of renaming the title:

• cleanup_web_submissions.yml and sync_develop_with_master.yml match on the brain-score.org submission prefix, and score_new_plugins.yml parses (user:) / (public:) out of it.
• The release gate ignores plugin folders, so these merges never release whatever their title.
• The fork check (head.repo.full_name == github.repository) means only branches pushed to the repo itself are exempt.

This applies to vision and language right away, because both call this workflow at @main.

After merge
Re-run the PR title check on any open submission PR, or push to it.