ci: remove success message from formatting check

The workflow succeeds giving a green check-mark next to the commit id. Perhaps writing a comment each time is redundant?

E.g.: hapifhir#856

Author: MartinBernstorff

.github/workflows/spotless-check.yml

@@ -23,8 +23,6 @@ jobs:
          if: always()
          with:
            proxy-url: https://slack-bots.azure.smilecdr.com/robogary/github
-           message-success: |
-             Formatting check succeeded!
            message-failure: |
              **This Pull Request has failed the formatting check**