Don't lock using GitHub actions (#29913)

We have our bot for this. See:
- https://github.com/GiteaBot/gitea-backporter?tab=readme-ov-file#locks
- https://github.com/GiteaBot/gitea-backporter/blob/main/src/lock.ts

Signed-off-by: Yarden Shoham <git@yardenshoham.com>
Co-authored-by: silverwind <me@silverwind.io>

.github/workflows/cron-lock.yml

@@ -1,23 +0,0 @@
-name: cron-lock
-
-on:
-  schedule:
-    - cron: "0 0 * * *" # every day at 00:00 UTC
-  workflow_dispatch:
-
-permissions:
-  issues: write
-  pull-requests: write
-
-concurrency:
-  group: lock
-
-jobs:
-  action:
-    runs-on: ubuntu-latest
-    if: github.repository == 'go-gitea/gitea'
-    steps:
-      - uses: dessant/lock-threads@v5
-        with:
-          issue-inactive-days: 10
-          pr-inactive-days: 7