Disable warning: ignoring temporary created by a constructor declared with 'nodiscard' attribute

```
frameworks/native/services/surfaceflinger/Scheduler/Scheduler.cpp:492:29: error: ignoring tempora
ry created by a constructor declared with 'nodiscard' attribute [-Werror,-Wunused-value]
  492 |                            (std::scoped_lock(mDisplayLock), displayId == mPacesetterDispl
ayId));
      |                             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
frameworks/native/include/ftl/fake_guard.h:85:72: note: expanded from macro 'FTL_FAKE_GUARD'
   85 |   FTL_MAKE_FAKE_GUARD(__VA_ARGS__, FTL_FAKE_GUARD2, FTL_FAKE_GUARD1, )(__VA_ARGS__)
      |                                                                        ^~~~~~~~~~~
frameworks/native/include/ftl/fake_guard.h:80:38: note: expanded from macro 'FTL_FAKE_GUARD2'
   80 |     (android::ftl::FakeGuard(mutex), expr)
      |                                      ^~~~
frameworks/native/services/surfaceflinger/Scheduler/Scheduler.cpp:916:27: error: ignoring temporary created by a constructor declared with 'nodiscard' attribute [-Werror,-Wunused-value]
```

Flag: EXEMPT b/369277774
Bug: b/369277774
Change-Id: I6b89de7a127753e435ab70b3ff392e0a84ecc31c