[code coverage] Use clang coverage instrumentation on linux-rel

This CL uses clang coverage instrumentation on linux-rel and turns it
off on linux-coverage-rel.

Bug: 930364
Change-Id: I1a251a70ede8e4cc9567cbbcab715e0cc5cd2fb8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1709091Reviewed-by: Aaron Gable <agable@chromium.org>
Reviewed-by: Nodir Turakulov <nodir@chromium.org>
Reviewed-by: Stephen Martinis <martiniss@chromium.org>
Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#680532}

tools/mb/mb_config.pyl

@@ -747,13 +747,13 @@
       'linux-annotator-rel': 'release_trybot',
       'linux-blink-heap-concurrent-marking-tsan-rel': 'release_trybot_tsan',
       'linux-blink-heap-verification-try': 'release_trybot_enable_blink_heap_verification',
-      'linux-coverage-rel': 'gpu_tests_release_trybot_no_symbols_use_dummy_lastchange_code_coverage',
+      'linux-coverage-rel': 'gpu_tests_release_trybot_no_symbols_use_dummy_lastchange',
       'linux-dcheck-off-rel': 'release_trybot_dcheck_off',
       'linux-gcc-rel': 'release_bot_x86_minimal_symbols_no_clang_cxx11',
       'linux-jumbo-rel': 'jumbo_large_chunks_release_bot_compile_only',
       'linux-libfuzzer-asan-rel': 'libfuzzer_asan_release_trybot',
       'linux-ozone-rel': 'ozone_linux_release_trybot',
-      'linux-rel': 'gpu_tests_release_trybot_no_symbols_use_dummy_lastchange',
+      'linux-rel': 'gpu_tests_release_trybot_no_symbols_use_dummy_lastchange_code_coverage',
       'linux-trusty-rel': 'gpu_tests_release_trybot_no_symbols_use_dummy_lastchange',
       'linux-webkit-msan-rel': 'msan_release_bot',
       'linux_arm': 'release_trybot_arm',