[test] Move mac-arm64 testing to chromium.test

The Chromium testing pool now has a sufficient number of devices for
testing. The old pool is deprecated.

No-Try: true
Bug: chromium:1226561
Change-Id: I6a985da860d4d2d5a30ccfd2c6593cce54b930c4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3006414
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75561}

infra/testing/builders.pyl

@@ -761,7 +761,7 @@
     'swarming_dimensions' : {
       'cpu': 'arm64',
       'os': 'Mac-11',
-      'pool': 'chromium.tests.mac-arm64',
+      'pool': 'chromium.tests',
     },
     'tests': [
       {'name': 'v8testing'},
@@ -771,7 +771,7 @@
     'swarming_dimensions' : {
       'cpu': 'arm64',
       'os': 'Mac-11',
-      'pool': 'chromium.tests.mac-arm64',
+      'pool': 'chromium.tests',
     },
     'tests': [
       {'name': 'v8testing'},
@@ -781,7 +781,7 @@
     'swarming_dimensions' : {
       'cpu': 'arm64',
       'os': 'Mac-11',
-      'pool': 'chromium.tests.mac-arm64',
+      'pool': 'chromium.tests',
     },
     'tests': [
       {'name': 'v8testing'},
@@ -1493,7 +1493,7 @@
     'swarming_dimensions' : {
       'os': 'Mac-11',
       'cpu': 'arm64',
-      'pool': 'chromium.tests.mac-arm64',
+      'pool': 'chromium.tests',
     },
     'swarming_task_attrs': {
       'expiration': 14400,
@@ -1509,7 +1509,7 @@
     'swarming_dimensions' : {
       'os': 'Mac-11',
       'cpu': 'arm64',
-      'pool': 'chromium.tests.mac-arm64',
+      'pool': 'chromium.tests',
     },
     'swarming_task_attrs': {
       'expiration': 14400,