Fix disappearing redbox on initial load of an invalid bundle. (#50867)

Summary:
Right now having a javascript error like an invalid import statement during first bundle load results in a disappearing redbox screen.

https://github.com/user-attachments/assets/ab9c64f5-6e32-481c-a58f-6d37bb920acb

The `invalidate` call removed in this PR cleans up all turbomodules, including the RedBox module, which in turns calls `dismiss` in `RCTRedBox`.

After removing this line the result is as following:

https://github.com/user-attachments/assets/6eeb4d43-f883-440f-ade3-5628f85f833a

I made sure that the `invalidate` function is still called when executing only two possible ways to reload the bundle:
- the Reload button
- Cmd+R

The HMR/hot reload is not connected if the bundle has an error on initial load, so we don't need to worry about it.

Longer term, it would be better to establish HMR and use a different redbox in this case:

![simulator_screenshot_DFF4EA47-DA12-46A9-81DF-9904B35EB1D9](https://github.com/user-attachments/assets/c46eb0e9-845a-4b62-96e2-74215cbdad18)

Doing this requires larger changes to the bundle loading flow – happy to to try and land that change if there's any guidance you could give.

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[IOS][FIXED] – Fix disappearing redbox on initial load of an invalid bundle.

Pull Request resolved: #50867

Test Plan: I have tested this change using RN from main and RNTester app (see videos).

Reviewed By: cortinico

Differential Revision: D73511154

Pulled By: cipolleschi

fbshipit-source-id: dfe149ebc15d845f07fd3926db2e063b468870af

Author: aleqsio

packages/react-native/ReactCommon/react/runtime/platform/ios/ReactCommon/RCTInstance.mm

@@ -507,7 +507,6 @@ - (void)_loadJSBundle:(NSURL *)sourceURL
 
         if (error) {
           [strongSelf handleBundleLoadingError:error];
-          [strongSelf invalidate];
           return;
         }
         // DevSettings module is needed by _loadScriptFromSource's callback so prior initialization is required