Remove galleries list action (#17648)

.github/workflows/update-galleries-list-reminder.yml

@@ -1,20 +0,0 @@
-name: Update Extension Gallery Reminder
-on:
-  pull_request:
-    paths:
-      - 'extensionsGallery.json'
-    branches:
-      - release/extensions
-
-jobs:
-  main:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: mshick/add-pr-comment@v1
-        with:
-          message: |
-            This is a reminder to update the Extensions Gallery list at https://github.com/Microsoft/azuredatastudio/wiki/List-of-Extensions once this PR has been merged in.
-            Instructions for doing this can be found [here](https://github.com/microsoft/azuredatastudio-docs/blob/main/Guides/UpdateExtensionGallery.md#guide-for-extension-release-dri).
-
-          repo-token: ${{ secrets.GITHUB_TOKEN }}
-          repo-token-user-login: 'github-actions[bot]' # The user.login for temporary GitHub tokens