The splitStatements function naively split on every semicolon, breaking
CREATE TRIGGER definitions that contain semicolons inside their
BEGIN...END bodies. Now tracks depth so trigger bodies are kept intact.
Fixes TestWebhook_ParticipantLeft_NoDoubleBroadcast_AfterFreshCleanup
and TestWebhook_ParticipantLeft_OldToken_DoesNotTeardownReplacement.