OZG-7473 extract regex to const

Based on CR comment.

alfa-client/libs/tech-shared/src/lib/validation/tech.validation.util.ts

@@ -111,5 +111,6 @@ export function getFieldPath(name: string, pathPrefix: string): string {
 }
 
 export function _mapFormArrayElementNameToPath(name: string): string {
-  return name.replace(/\[(\d+?)]\./g, '.$1.');
+  const formArrayControlIndexCaptureGroup: RegExp = /\[(\d+?)]\./g;
+  return name.replace(formArrayControlIndexCaptureGroup, '.$1.');
 }