Remove support for dimension sets.

With all other uses switched to disable dimension sets, this removes
support for dimension sets. The --dimension-sets-handling flag is
retained because it is being set in the dependency uses, but it can't be
set to any value besides disable and doesn't impact any behavior.

Bug: 1466328
Change-Id: I8abeaef38e6d0e926076fd8bd31dc8cb9423fbf8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4749287
Reviewed-by: Ben Pastene <[email protected]>
Commit-Queue: Garrett Beaty <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1179854}
diff --git a/testing/buildbot/mixins.pyl b/testing/buildbot/mixins.pyl
index ca90584..efb87aa 100644
--- a/testing/buildbot/mixins.pyl
+++ b/testing/buildbot/mixins.pyl
@@ -201,14 +201,12 @@
       '--magic-vm-cache=magic_cros_vm_cache',
     ],
     'swarming': {
-      'dimension_sets': [
-        {
-          'cpu': 'x86',
-          'kvm': '1',
-          'os': 'Ubuntu-22.04',
-          'pool': 'chromium.tests',
-        },
-      ],
+      'dimensions': {
+        'cpu': 'x86',
+        'kvm': '1',
+        'os': 'Ubuntu-22.04',
+        'pool': 'chromium.tests',
+      },
       'optional_dimensions': {
         '60': {
           'caches': 'cros_vm',
@@ -227,15 +225,13 @@
       '--magic-vm-cache=magic_cros_vm_cache',
     ],
     'swarming': {
-      'dimension_sets': [
-        {
-          'cpu': 'x86',
-          'kvm': '1',
-          'gce': '1',
-          'os': 'Ubuntu-22.04',
-          'pool': 'chrome.tests',
-        },
-      ],
+      'dimensions': {
+        'cpu': 'x86',
+        'kvm': '1',
+        'gce': '1',
+        'os': 'Ubuntu-22.04',
+        'pool': 'chrome.tests',
+      },
       'optional_dimensions': {
         '60': {
           'caches': 'cros_vm',
@@ -255,15 +251,13 @@
       '--magic-vm-cache=magic_cros_vm_cache',
     ],
     'swarming': {
-      'dimension_sets': [
-        {
-          'cpu': 'x86',
-          'kvm': '1',
-          'gce': '1',
-          'os': 'Ubuntu-22.04',
-          'pool': 'chrome.tests.finch',
-        },
-      ],
+      'dimensions': {
+        'cpu': 'x86',
+        'kvm': '1',
+        'gce': '1',
+        'os': 'Ubuntu-22.04',
+        'pool': 'chrome.tests.finch',
+      },
       'optional_dimensions': {
         '60': {
           'caches': 'cros_vm',
@@ -307,15 +301,13 @@
       '--magic-vm-cache=magic_cros_reven_vm_cache',
     ],
     'swarming': {
-      'dimension_sets': [
-        {
-          'cpu': 'x86',
-          'kvm': '1',
-          'gce': '1',
-          'os': 'Ubuntu-18.04',
-          'pool': 'chrome.tests',
-        },
-      ],
+      'dimensions': {
+        'cpu': 'x86',
+        'kvm': '1',
+        'gce': '1',
+        'os': 'Ubuntu-18.04',
+        'pool': 'chrome.tests',
+      },
       'optional_dimensions': {
         '60': {
           'caches': 'cros_reven_vm',
@@ -844,12 +836,10 @@
   },
   'mac_x64': {
     'swarming': {
-      'dimension_sets': [
-        {
-          'os': 'Mac-12',
-          'cpu': 'x86-64',
-        },
-      ],
+      'dimensions': {
+        'os': 'Mac-12',
+        'cpu': 'x86-64',
+      },
     },
   },
   'marshmallow': {