Promote chrome_sizes on chromium.chrome bots out of experimental.

Got green runs on the three desktop bots:
https://ci.chromium.org/p/chrome/builders/ci/linux-google-rel/5659
https://ci.chromium.org/p/chrome/builders/ci/win-google-rel/5994
https://ci.chromium.org/p/chrome/builders/ci/mac-google-rel/2935

And trybot mirrors are not polluting the perf dashboard's streams for the
CI bots since they upload to a different namespace based on master:
https://codesearch.chromium.org/chromium/src/tools/perf/core/perf_dashboard_machine_group_mapping.json

Bug: 961548
Change-Id: I9aae3c16eda8b2758e47a80f31a717c8c69f8772
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1656017Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672102}

testing/buildbot/chromium.chrome.json

@@ -2147,7 +2147,6 @@
     ],
     "isolated_scripts": [
       {
-        "experiment_percentage": 100,
         "isolate_name": "chrome_sizes",
         "merge": {
           "script": "//tools/perf/process_perf_results.py"
@@ -2170,7 +2169,6 @@
     ],
     "isolated_scripts": [
       {
-        "experiment_percentage": 100,
         "isolate_name": "chrome_sizes",
         "merge": {
           "script": "//tools/perf/process_perf_results.py"
@@ -2207,7 +2205,6 @@
     ],
     "isolated_scripts": [
       {
-        "experiment_percentage": 100,
         "isolate_name": "chrome_sizes",
         "merge": {
           "script": "//tools/perf/process_perf_results.py"

testing/buildbot/test_suites.pyl

@@ -208,9 +208,6 @@
         'merge': {
           'script': '//tools/perf/process_perf_results.py',
         },
-        # TODO(crbug.com/961548): Promote these out of experiment if/when they
-        # pass.
-        'experiment_percentage': 100,
       },
     },