[MM-28131] Fix desanitization of DataSourceReplicas and DataSourceSearchReplicas (#15389)

* Fix desanitization of DataSourceReplicas and DataSourceSearchReplicas

* Fix test case

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

config/utils.go

@@ -52,14 +52,20 @@ func desanitize(actual, target *model.Config) {
 		*target.ElasticsearchSettings.Password = *actual.ElasticsearchSettings.Password
 	}
 
-	target.SqlSettings.DataSourceReplicas = make([]string, len(actual.SqlSettings.DataSourceReplicas))
-	for i := range target.SqlSettings.DataSourceReplicas {
-		target.SqlSettings.DataSourceReplicas[i] = actual.SqlSettings.DataSourceReplicas[i]
+	if len(target.SqlSettings.DataSourceReplicas) == len(actual.SqlSettings.DataSourceReplicas) {
+		for i, value := range target.SqlSettings.DataSourceReplicas {
+			if value == model.FAKE_SETTING {
+				target.SqlSettings.DataSourceReplicas[i] = actual.SqlSettings.DataSourceReplicas[i]
+			}
+		}
 	}
 
-	target.SqlSettings.DataSourceSearchReplicas = make([]string, len(actual.SqlSettings.DataSourceSearchReplicas))
-	for i := range target.SqlSettings.DataSourceSearchReplicas {
-		target.SqlSettings.DataSourceSearchReplicas[i] = actual.SqlSettings.DataSourceSearchReplicas[i]
+	if len(target.SqlSettings.DataSourceSearchReplicas) == len(actual.SqlSettings.DataSourceSearchReplicas) {
+		for i, value := range target.SqlSettings.DataSourceSearchReplicas {
+			if value == model.FAKE_SETTING {
+				target.SqlSettings.DataSourceSearchReplicas[i] = actual.SqlSettings.DataSourceSearchReplicas[i]
+			}
+		}
 	}
 
 	if *target.MessageExportSettings.GlobalRelaySettings.SmtpPassword == model.FAKE_SETTING {