ci: switch to explicit commit message body for renovate (angular#46676)

The commit body table by Renovate is sometimes not generated e.g. when
just dev-infra is being updated. In order to make our lint job happy
for such dev-infra updates, we should use an explicit message that is
at least 20 characters long.

PR Close angular#46676

Author: devversion

renovate.json

@@ -9,7 +9,7 @@
   "semanticCommitScope": "",
   "semanticCommitType": "build",
   "dependencyDashboard": true,
-  "commitBodyTable": true,
+  "commitBody": "See associated pull request for more information.",
   "separateMajorMinor": false,
   "prHourlyLimit": 3,
   "timezone": "America/Tijuana",