[native] regenerate backup on every password change

Summary:
[ENG-8070](https://linear.app/comm/issue/ENG-8070/regenerate-backup-on-every-password-change)

Some concerns are listed the comment in [ENG-8070](https://linear.app/comm/issue/ENG-8070/regenerate-backup-on-every-password-change#comment-a0fd33ac).

Depends on D14063

Test Plan: On primary device, change password and check that new backup was uploaded

Reviewers: bartek, tomek

Reviewed By: bartek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D14065

lib/reducers/backup-reducer.js

@@ -1,6 +1,7 @@
 // @flow
 
 import { createUserKeysBackupActionTypes } from '../actions/backup-actions.js';
+import { changeIdentityUserPasswordActionTypes } from '../actions/user-actions.js';
 import type { BackupStore } from '../types/backup-types.js';
 import type { BaseAction } from '../types/redux-types.js';
 
@@ -13,6 +14,10 @@ function reduceBackupStore(
     return {
       latestBackupInfo,
     };
+  } else if (action.type === changeIdentityUserPasswordActionTypes.success) {
+    return {
+      latestBackupInfo: null,
+    };
   }
   return store;
 }