Move arc-r builders to their own builder_group.

The current builder_group is proving difficult due to recipe reasons.

A whole new builder_group should be easier.

Bug: 1129540
Change-Id: Iee101b7f915ec158d3b761408a36e6fc62c4da21
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2419134Reviewed-by: Garrett Beaty <gbeaty@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808486}

testing/buildbot/generate_buildbot_json.py

@@ -1442,7 +1442,7 @@ class BBJSONGenerator(object):
   def get_internal_waterfalls(self):
     # Similar to get_builders_that_do_not_actually_exist above, but for
     # waterfalls defined in internal configs.
-    return ['chrome', 'chrome.pgo', 'internal.chrome.fyi', 'internal.soda']
+    return ['chrome', 'chrome.pgo', 'internal.chromeos.fyi', 'internal.soda']
 
   def check_input_file_consistency(self, verbose=False):
     self.check_input_files_sorting(verbose)

testing/buildbot/waterfalls.pyl

@@ -5521,7 +5521,7 @@
   {
     'project': 'chrome',
     'bucket': 'ci',
-    'name': 'internal.chrome.fyi',
+    'name': 'internal.chromeos.fyi',
     'mixins': ['chrome-tester-service-account'],
     'machines': {
       'chromeos-betty-arc-r-chrome': {

tools/mb/mb_config.pyl

@@ -666,8 +666,6 @@
 
     'internal.chrome.fyi': {
       'chromeos-amd64-generic-lacros-internal-rel': 'chromeos_amd64-generic_lacros_rel',
-      'chromeos-betty-arc-r-chrome': 'chromeos_betty-arc-r_include_unwind_tables_official_use_fake_dbus_clients',
-      'chromeos-eve-arc-r-chrome': 'chromeos_eve-arc-r_include_unwind_tables_official',
       'linux-autofill-captured-sites-rel': 'release_bot',
       'linux-password-manager-captured-sites-rel': 'release_bot',
       'lorenz-graph-dbg': 'android_debug_static_bot',
@@ -677,6 +675,11 @@
       'win-password-manager-captured-sites-rel': 'release_bot',
     },
 
+    'internal.chromeos.fyi': {
+      'chromeos-betty-arc-r-chrome': 'chromeos_betty-arc-r_include_unwind_tables_official_use_fake_dbus_clients',
+      'chromeos-eve-arc-r-chrome': 'chromeos_eve-arc-r_include_unwind_tables_official',
+    },
+
     'internal.client.kitchensync': {
       'Linux Canary': 'debug_bot',
       'Linux Dev': 'debug_bot',