gerrit: only backup accountPatchReviewDb

Due to [1] --all-databases is no longer working with our version of
database.  Move to explicitly backing up the only database we care
about now, which is accountPatchReviewDb; everything else is in
notedb.

[1] https://bugs.launchpad.net/ubuntu/+source/mysql-5.7/+bug/1914695

Change-Id: Iab2a8ab612cc0a0f10c90123f2936c0abda9e76f

playbooks/roles/gerrit/tasks/main.yaml

@@ -326,7 +326,7 @@
     user: root
     hour: 0
     minute: 0
-    job: '/usr/bin/mysqldump --defaults-file=/root/.gerrit_db.cnf --opt --ignore-table mysql.event --all-databases --single-transaction | gzip -9 > /home/gerrit2/mysql_backups/gerrit.sql.gz'
+    job: '/usr/bin/mysqldump --defaults-file=/root/.gerrit_db.cnf --opt --ignore-table mysql.event --single-transaction --databases accountPatchReviewDb | gzip -9 > /home/gerrit2/mysql_backups/gerrit.sql.gz'
 
 # Gerrit rotates their own logs, but doesn't clean them out
 # Delete logs older than a month
@@ -346,8 +346,17 @@
         path: /etc/borg-streams
         state: directory
 
-    - name: Create db streaming file
+    # NOTE(ianw) 2021-02-09 --all-databases stopped working with
+    # Xenial/our rax version of mysql so we have to backup db's
+    # explicitly.  remove the old call.  This can go after a
+    # deployment run.
+    - name: Remove old stream backup
+      file:
+        state: absent
+        path: /etc/borg-streams/mysql
+
+    - name: Create accountPatchReviewDb streaming file
       copy:
         content: >-
-          /usr/bin/mysqldump --defaults-file=/root/.gerrit_db.cnf --skip-extended-insert --ignore-table mysql.event --all-databases --single-transaction
-        dest: /etc/borg-streams/mysql
+          /usr/bin/mysqldump --defaults-file=/root/.gerrit_db.cnf --skip-extended-insert --ignore-table mysql.event --single-transaction --databases accountPatchReviewDb
+        dest: /etc/borg-streams/mysql-accountPatchReviewDb