As documented in https://docs.google.com/document/d/1GT7r2oFtmp0Nc3UNZ1L_GFe85ozfyAG2vI7jsPrNCSQ/edit,
webhook sink is excessively slow. Not clear if some temporary fixes are possible here.
However, the combination of slow sink plus a very slow mock webhook sink implementation, make
any webhook-tests excessively slow. A single message processing takes 50ms, and some times over 1s per message,
in a local test.

Jira issue: CRDB-17793

Epic CRDB-11356