infra: Use os=MAC_ANY for iOS Goma RBE ToT builders

This is the os value used by other iOS Goma RBE builders.

R=tikuta@chromium.org, ukai@chromium.org, yekuang@google.com, yyanagisawa@chromium.org

Bug: 1063727
Change-Id: I1df2def9f0e3d1d5dc79d711188494550ffc4d8c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2114312Reviewed-by: Yoshisato Yanagisawa <yyanagisawa@google.com>
Commit-Queue: Simon Que <sque@chromium.org>
Cr-Commit-Position: refs/heads/master@{#752366}

infra/config/buckets/goma.star

@@ -439,12 +439,12 @@ goma_builder(
 )
 
 
-def goma_mac_builder(*, name, **kwargs):
+def goma_mac_builder(*, name, os=os.MAC_DEFAULT, **kwargs):
   return goma_builder(
       name = name,
       cores = 4,
       goma_jobs = goma.jobs.J80,
-      os = os.MAC_DEFAULT,
+      os = os,
       **kwargs
   )
 
@@ -453,6 +453,7 @@ goma_mac_builder(
     caches = [xcode_cache.x11c29],
     executable = 'recipe:ios/unified_builder_tester',
     goma_backend = goma.backend.RBE_TOT,
+    os = os.MAC_ANY,
 )
 
 goma_mac_builder(

infra/config/generated/cr-buildbucket.cfg

@@ -12250,7 +12250,7 @@ buckets: <
       dimensions: "builder:Chromium iOS Goma RBE ToT"
       dimensions: "cores:4"
       dimensions: "cpu:x86-64"
-      dimensions: "os:Mac-10.13"
+      dimensions: "os:Mac"
       dimensions: "pool:luci.chromium.ci"
       recipe: <
         name: "ios/unified_builder_tester"