sqlcapture: Fix error shutdown edge case

This probably doesn't make a real difference since the only time
we might fail to cancel the commit-buffering worker context would
be if an error occurred and the connector was shutting down anyway,
but we might as well satisfy the static analysis warning.

Author: willdonnelly

sqlcapture/capture.go

@@ -578,6 +578,7 @@ func (c *Capture) streamToFence(ctx context.Context, replStream ReplicationStrea
 		event       CommitEvent // When we have a buffered commit event which hasn't yet been processed or invalidated, this is it. Otherwise it's nil.
 	}
 	var workerCtx, cancelWorkerCtx = context.WithCancel(ctx) // Context for the commit buffering worker goroutine
+	defer cancelWorkerCtx()                                  // Ensure that the worker goroutine always exits when we do
 	var workerGroup errgroup.Group
 	workerGroup.Go(func() error {
 		var ticker = time.NewTicker(commitBufferingInterval)