fix: avoid calling Timing.deleteTimer for setImmediate and requestIdleCallback (#26113)

Summary:
Fix a simple error where `types[index]` was being accessed after it was cleared, instead of before.

## Changelog

[iOS] [Fixed] - never call deleteTimer for setImmediate and requestIdleCallback
Pull Request resolved: https://github.com/facebook/react-native/pull/26113

Test Plan: None

Differential Revision: D17314489

Pulled By: cpojer

fbshipit-source-id: 74715f0f7cc2d5cee3b97a67313c5e96e9d6c555

Libraries/Core/Timers/JSTimers.js

@@ -218,8 +218,8 @@ function _freeCallback(timerID: number) {
   const index = timerIDs.indexOf(timerID);
   // See corresponding comment in `callTimers` for reasoning behind this
   if (index !== -1) {
-    _clearIndex(index);
     const type = types[index];
+    _clearIndex(index);
     if (type !== 'setImmediate' && type !== 'requestIdleCallback') {
       deleteTimer(timerID);
     }