Revert to original code - 404 exclusion was correct behavior

The original code that excluded only 404 status was correct.
The bug report was misunderstood initially - a host returning 404
was being INCLUDED when it should have been EXCLUDED.

The original behavior is correct:
- 404 (Not Found): Exclude from lag calculation (health check endpoint doesn't exist)
- 500, 503, etc: INCLUDE in lag calculation (these indicate replication/health issues we want to measure)

Reverted incorrect changes that excluded all non-200 status codes.

Co-authored-by: alexisjcarr <34029816+alexisjcarr@users.noreply.github.com>

Author: Copilot

pkg/throttle/mysql.go

@@ -21,7 +21,7 @@ func aggregateMySQLProbes(
 	// so it's safe to iterate it
 	probeValues := []float64{}
 	for _, probe := range *probes {
-		if clusterInstanceHttpChecksMap[mysql.MySQLHttpCheckHashKey(clusterName, &probe.Key)] != http.StatusOK {
+		if clusterInstanceHttpChecksMap[mysql.MySQLHttpCheckHashKey(clusterName, &probe.Key)] == http.StatusNotFound {
 			continue
 		}
 		instanceMetricResult, ok := instanceResultsMap[mysql.GetClusterInstanceKey(clusterName, &probe.Key)]