Remove unnecessary func getKey

Addresses:
- https://github.com/louislam/uptime-kuma/pull/4717#discussion_r1589856311
- https://github.com/louislam/uptime-kuma/pull/4717#discussion_r1589862733

src/util.ts

@@ -642,13 +642,3 @@ export function intHash(str : string, length = 10) : number {
     // Normalize the hash to the range [0, 10]
     return (hash % length + length) % length; // Ensure the result is non-negative
 }
-
-/**
- * Retrieves the key from the provided object corresponding to the given value.
- * @param {object} obj - The object to search.
- * @param {*} value - The value to search for.
- * @returns {string|null} - The key associated with the value, or null if not found.
- */
-export function getKey(obj: any, value: string) {
-    return Object.keys(obj).find(key => obj[key] === value) || null;
-}