Revert "Run GPU-less tests on macOS 11 bots."

This reverts commit 10bb40a03d63a5d94050b05a93a6560abc6ddef9.

Reason for revert: no Mac-11 in luci.flex

Original change's description:
> Run GPU-less tests on macOS 11 bots.
>
> Bug: chromium:1273555
> Change-Id: Ifcbdccd930180d2df28e8ab7b1b6e3ef93f8564b
> Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/70940
> Reviewed-by: Ryan Harrison <rharrison@chromium.org>
> Commit-Queue: Corentin Wallez <cwallez@chromium.org>

TBR=cwallez@chromium.org,rharrison@chromium.org,dawn-scoped@luci-project-accounts.iam.gserviceaccount.com

Change-Id: Ic8e70238b78c6cc37d95215d63eced52cf069573
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:1273555
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/70942
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
diff --git a/infra/config/global/generated/cr-buildbucket.cfg b/infra/config/global/generated/cr-buildbucket.cfg
index 54f656b..3a4e486 100644
--- a/infra/config/global/generated/cr-buildbucket.cfg
+++ b/infra/config/global/generated/cr-buildbucket.cfg
@@ -140,7 +140,7 @@
       name: "mac-dbg"
       swarming_host: "chromium-swarm.appspot.com"
       dimensions: "cpu:x86-64"
-      dimensions: "os:Mac-11"
+      dimensions: "os:Mac-10.15"
       dimensions: "pool:luci.flex.ci"
       recipe {
         name: "dawn"
@@ -169,7 +169,7 @@
       name: "mac-rel"
       swarming_host: "chromium-swarm.appspot.com"
       dimensions: "cpu:x86-64"
-      dimensions: "os:Mac-11"
+      dimensions: "os:Mac-10.15"
       dimensions: "pool:luci.flex.ci"
       recipe {
         name: "dawn"
@@ -482,7 +482,7 @@
       name: "mac-dbg"
       swarming_host: "chromium-swarm.appspot.com"
       dimensions: "cpu:x86-64"
-      dimensions: "os:Mac-11"
+      dimensions: "os:Mac-10.15"
       dimensions: "pool:luci.flex.try"
       recipe {
         name: "dawn"
@@ -512,7 +512,7 @@
       name: "mac-rel"
       swarming_host: "chromium-swarm.appspot.com"
       dimensions: "cpu:x86-64"
-      dimensions: "os:Mac-11"
+      dimensions: "os:Mac-10.15"
       dimensions: "pool:luci.flex.try"
       recipe {
         name: "dawn"
diff --git a/infra/config/global/generated/project.cfg b/infra/config/global/generated/project.cfg
index 79430cc..4d04895 100644
--- a/infra/config/global/generated/project.cfg
+++ b/infra/config/global/generated/project.cfg
@@ -7,7 +7,7 @@
 name: "dawn"
 access: "group:all"
 lucicfg {
-  version: "1.30.4"
+  version: "1.30.1"
   package_dir: ".."
   config_dir: "generated"
   entry_point: "main.star"
diff --git a/infra/config/global/main.star b/infra/config/global/main.star
index 6224ff3..609d207 100755
--- a/infra/config/global/main.star
+++ b/infra/config/global/main.star
@@ -113,7 +113,7 @@
 
 os = struct(
     LINUX = os_enum("Ubuntu-18.04", os_category.LINUX, "linux"),
-    MAC = os_enum("Mac-11", os_category.MAC, "mac"),
+    MAC = os_enum("Mac-10.15", os_category.MAC, "mac"),
     WINDOWS = os_enum("Windows-10", os_category.WINDOWS, "win"),
 )