[utils] Fixes death test conditions and macros.

In https://dawn-review.git.corp.google.com/c/dawn/+/339076, when
trying to get partition_alloc death tests working for RawSpan,
I unconditionally imported:
  //build/config/sanitizers/sanitizers.gni
By importing that config, the use_fuzzing_engine flag was flipped
to "true" when the gn arg use_libfuzzer was set to "true". (This
happens in the clusterfuzz CI bot linked in the bug.) This
caused all the compilation flags of:
  DAWN_ENABLE_ASSERTS
  DAWN_ABORT_ON_ASSERT
  DAWN_DISABLE_LOGGING
to be set at compilation time. At the same time, that CI bot
actually sets is_debug = false, which meant that the
DAWN_EXPECT_DEBUG_DEATH_IF_SUPPORTED macro assumed the test should
not crash, when in reality it does because DAWN_ENABLE_ASSERT
is the real flag that decides whether we crash or not and it
was set because use_fuzzing_engine was true.

This change does two main things:
  1) Fix the condition in utils/BUILD.gn such that we only set
     DAWN_ENABLE_ASSERTS w.r.t use_fuzzing_engine when we are
     building as a part of Chromium. This reverts the behavior
     of the tests to be the same as before the change above.
     Specifically, that the standalone clusterfuzz build does
     not build with asserts enabled since standalone builds
     depend on the is_debug flag to determine whether they
     should be enabled.
  2) Updates the test macros in utils/gtest.h to more
     explicitly handle the different cases appropriately so that
     tests don't need to handle them with ifdefs. This includes:
       - Adding DAWN_EXPECT_DEATH_IF_SUPPORTED macros that
         automatically suppresses string matching on the error
	 logs when DAWN_DISABLE_LOGGING in enabled.
       - Update DAWN_*_DEBUG_DEATH_IF_SUPPORTED macros to check
         both if we are in debug mode, or if DAWN_ENABLE_ASSERTS
	 is explicitly enabled.
       - Update PRESUBMIT.py to prevent Dawn code from using the
         gtest native macros, and instead make tests use the Dawn
	 ones that handle the different compilation defines
	 appropriately.
       - Update existing test code to use the new macros.

Bug: 564917473
Change-Id: Ia3e5cc597d9bcc7288cc3d66f16ce136d2f7db63
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/344475
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Loko Kung <lokokung@google.com>