Close only bot issues from github-actions by l10n cron job (#14604)

* Close out only [bot] issues by cron

* Improve l10n routine strings

.github/workflows/routine_l10n_obsolete.yml

@@ -1,20 +1,21 @@
-name: Create l10n cleanup task
+name: Bimonthly l10n cleanup reminder
 on:
   schedule:
     - cron: 0 09 14 */2 *
 
 jobs:
   create_issue:
-    name: Create l10n cleanup task
+    name: Create l10n cleanup issue
     runs-on: ubuntu-latest
     permissions:
       issues: write
     steps:
-      - name: Create l10n cleanup task
+      - name: Open new issue (and close old if needed)
         run: |
           if [[ $CLOSE_PREVIOUS == true ]]; then
             previous_issue_number=$(gh issue list \
               --label "$LABELS" \
+              --author "github-actions[bot]" \
               --json number \
               --jq '.[0].number')
             if [[ -n $previous_issue_number ]]; then
@@ -33,13 +34,13 @@ jobs:
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           GH_REPO: ${{ github.repository }}
-          TITLE: Remove obsolete l10n strings and ftl files
+          TITLE: "[bot] Remove obsolete l10n strings and ftl files"
           ASSIGNEES:
           LABELS: L10N
           BODY: |
             ### Remove obsolete strings
 
-            Search the code base for strings marked `obsolete` that are more than 2 months old.
+            Search the code base for [strings marked `obsolete`](https://github.com/search?q=repo%3Amozilla%2Fbedrock+obsolete+language%3AFluent&type=code&l=Fluent) that are more than 2 months old.
             If you find strings that have no date, either find the date by looking at git history
             or add an expiry date and leave it to be removed in 2 months.