Disable -Wunused-value for updatePhaseConfiguration

```
frameworks/native/services/surfaceflinger/Scheduler/Scheduler.cpp:492:29: error: ignoring temporary created by a constructor declared with 'nodiscard' attribute [-Werror,-Wunused-value]
  492 |                            (std::scoped_lock(mDisplayLock), displayId == mPacesetterDisplayId));
      |                             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```
Flag: EXEMPT b/369277774
Bug: b/369277774

Change-Id: I183f22a881120156211e3296f022c8e52a47a39f