HPCC-10266 Disable banner usage from users

Enable set banner messages to only administrators.

Signed-off by: Miguel Vazquez <miguel.vazquez@lexisnexis.com>
Merge pull request #5086 from miguelvazq/HPCC-10266

HPCC-10266 Disable banner usage from users

Reviewed-By: Gordon Smith <gordon.smith@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>