Removed experimental tag from Perf tests on MacOS

Representative perf tests have been running on chromium.gpu as
experimental. This change removes the experimental tag:

Stats of recent runs on chromium.gpu:
14 flakes in the last 920 runs (1.5% flake rate)

Bug: chromium:1000837
Change-Id: Ie6f6d85733f8b63d5cd69636976c1eab93f38250
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2081190Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Behdad Bakhshinategh <behdadb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#746518}

testing/buildbot/chromium.gpu.json

@@ -1947,7 +1947,6 @@
           "../../tools/perf/run_benchmark",
           "--benchmarks=rendering.desktop"
         ],
-        "experiment_percentage": 100,
         "isolate_name": "rendering_representative_perf_tests",
         "merge": {
           "args": [],
@@ -2393,7 +2392,6 @@
           "../../tools/perf/run_benchmark",
           "--benchmarks=rendering.desktop"
         ],
-        "experiment_percentage": 100,
         "isolate_coverage_data": true,
         "isolate_name": "rendering_representative_perf_tests",
         "merge": {
@@ -3266,7 +3264,6 @@
           "../../tools/perf/run_benchmark",
           "--benchmarks=rendering.desktop"
         ],
-        "experiment_percentage": 100,
         "isolate_name": "rendering_representative_perf_tests",
         "merge": {
           "args": [],
@@ -3742,7 +3739,6 @@
           "../../tools/perf/run_benchmark",
           "--benchmarks=rendering.desktop"
         ],
-        "experiment_percentage": 100,
         "isolate_coverage_data": true,
         "isolate_name": "rendering_representative_perf_tests",
         "merge": {

testing/buildbot/waterfalls.pyl

@@ -2417,7 +2417,7 @@
         'test_suites': {
           'gtest_tests': 'gpu_desktop_gtests',
           'gpu_telemetry_tests': 'gpu_common_telemetry_tests',
-          'isolated_scripts': 'rendering_desktop_representative_perf_tests_isolated_scripts_experimental',
+          'isolated_scripts': 'rendering_desktop_representative_perf_tests_isolated_scripts',
         },
       },
       'Mac Release (Intel) Code Coverage': {
@@ -2430,7 +2430,7 @@
         'test_suites': {
           'gtest_tests': 'gpu_desktop_gtests',
           'gpu_telemetry_tests': 'gpu_common_telemetry_tests',
-          'isolated_scripts': 'rendering_desktop_representative_perf_tests_isolated_scripts_experimental',
+          'isolated_scripts': 'rendering_desktop_representative_perf_tests_isolated_scripts',
         },
       },
       'Mac Retina Debug (AMD)': {
@@ -2453,7 +2453,7 @@
         'test_suites': {
           'gtest_tests': 'gpu_desktop_gtests',
           'gpu_telemetry_tests': 'gpu_common_telemetry_tests',
-          'isolated_scripts': 'rendering_desktop_representative_perf_tests_isolated_scripts_experimental',
+          'isolated_scripts': 'rendering_desktop_representative_perf_tests_isolated_scripts',
         },
       },
       'Mac Retina Release (AMD) Code Coverage': {
@@ -2466,7 +2466,7 @@
         'test_suites': {
           'gtest_tests': 'gpu_desktop_gtests',
           'gpu_telemetry_tests': 'gpu_common_telemetry_tests',
-          'isolated_scripts': 'rendering_desktop_representative_perf_tests_isolated_scripts_experimental',
+          'isolated_scripts': 'rendering_desktop_representative_perf_tests_isolated_scripts',
         },
       },
       'Win10 x64 Debug (NVIDIA)': {