Add a phenotype flag to force disable CMC GC.

This new flag (`runtime_native_boot.force_disable_uffd_gc`) has priority
over the flag that enables the CMC GC
(`runtime_native_boot.enable_uffd_gc_2`).

Bug: 251150519
Test: -
  1. Build with OVERRIDE_ENABLE_UFFD_GC=false
  2. See "Using CollectorTypeCC GC".
  3. adb shell device_config set_sync_disabled_for_tests persistent
  4. adb shell device_config put runtime_native_boot enable_uffd_gc_2 true
  5. adb reboot
  6. See odrefresh triggered on the reboot.
  7. See "Using CollectorTypeCMC GC".
  8. adb shell device_config put runtime_native_boot force_disable_uffd_gc true
  9. adb reboot
  10. See odrefresh triggered on the reboot.
  11. See "Using CollectorTypeCC GC".
Change-Id: I2a53ccadf7e2932969a80a0c86c1307a58abf47a
2 files changed