Chore: Migrate workflows to use create-github-app-token (#2142)

- Removes dependabot.yml as renovate will update grafana-sdk for us
- Migrates to `create-github-app-token`
- Pin workflows
- Removes is-compatible.yml I found that workflow not helping much but
creating an annoyingly long comment

Fixes https://github.com/grafana/oss-big-tent-squad/issues/144

.github/workflows/update-create-plugin.yml

@@ -7,10 +7,17 @@ on:
 
 permissions:
   contents: write
+  id-token: write # Needed for create-github-app-token
   pull-requests: write
 
 jobs:
   release:
     runs-on: ubuntu-latest
     steps:
-      - uses: grafana/plugin-actions/create-plugin-update@main
+      - id: get-github-token
+        uses: grafana/shared-workflows/actions/create-github-app-token@ae92934a14a48b94494dbc06d74a81d47fe08a40 # create-github-app-token/v0.2.2
+        with:
+          github_app: grafana-oss-big-tent
+      - uses: grafana/plugin-actions/create-plugin-update@244c3bc9c6eb94bc1dd6458ade2462499bbf0f5b #create-plugin-update/v2.0.1
+        with:
+          token: ${{ steps.get-github-token.outputs.token }}