Stale MutationObserver records abort callbacks for active observers

Description

The MutationObserver manager explicitly tolerates stale native records when an observer is disconnected between commit and mount. However, encountering one missing registration returns from the entire notification pass, dropping every later record and callback in the same native batch, including records for still-active observers.

Expected behavior

A stale record for a disconnected observer should be ignored while notification continues for all active observers in the batch, matching the equivalent ResizeObserver handling.

React Native Version

0.87.1 and current main

Affected Platforms

New Architecture - All

首先定位 MutationObserver 管理器并阅读其通知遍历，然后将其与 issue 中描述的等效 ResizeObserver 处理进行比较。确认缺少的注册会被忽略，并且同一原生批次中后续处于 active 状态的 observer 仍会收到它们的 callbacks。