infra: CrOS builder def funcs default to Goma RBE

chromiumos_builder() in both ci.star and try.star use Goma RBE backend
by default.

Bug: 1025325
Change-Id: I5997959592a1c9d4fb629541cc603ba22e8c1a60
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1948008Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Commit-Queue: Simon Que <sque@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720826}

infra/config/buckets/ci.star

@@ -434,64 +434,55 @@ def chromiumos_builder(*, name, **kwargs):
   return builder(
       name = name,
       mastername = 'chromium.chromiumos',
+      goma_backend = goma.backend.RBE_PROD,
       **kwargs
   )
 
 chromiumos_builder(
     name = 'Linux ChromiumOS Full',
-    goma_backend = goma.backend.RBE_PROD,
 )
 
 chromiumos_builder(
     name = 'chromeos-amd64-generic-asan-rel',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
 )
 
 chromiumos_builder(
     name = 'chromeos-amd64-generic-cfi-thin-lto-rel',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
 )
 
 chromiumos_builder(
     name = 'chromeos-amd64-generic-dbg',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
 )
 
 chromiumos_builder(
     name = 'chromeos-amd64-generic-rel',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
 )
 
 chromiumos_builder(
     name = 'chromeos-arm-generic-dbg',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
 )
 
 chromiumos_builder(
     name = 'chromeos-arm-generic-rel',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
 )
 
 chromiumos_builder(
     name = 'chromeos-kevin-rel',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
 )
 
 chromiumos_builder(
     name = 'linux-chromeos-dbg',
-    goma_backend = goma.backend.RBE_PROD,
 )
 
 chromiumos_builder(
     name = 'linux-chromeos-rel',
-    goma_backend = goma.backend.RBE_PROD,
 )
 
 

infra/config/buckets/try.star

@@ -472,12 +472,12 @@ def chromiumos_builder(*, name, **kwargs):
   return try_builder(
       name = name,
       mastername = 'tryserver.chromium.chromiumos',
+      goma_backend = goma.backend.RBE_PROD,
       **kwargs
   )
 
 chromiumos_builder(
     name = 'chromeos-amd64-generic-dbg',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
     tryjob = tryjob(
         location_regexp = [
@@ -489,33 +489,28 @@ chromiumos_builder(
 
 chromiumos_builder(
     name = 'chromeos-amd64-generic-cfi-thin-lto-rel',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
 )
 
 chromiumos_builder(
     name = 'chromeos-amd64-generic-rel',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
     tryjob = tryjob(),
 )
 
 chromiumos_builder(
     name = 'chromeos-arm-generic-dbg',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
 )
 
 chromiumos_builder(
     name = 'chromeos-arm-generic-rel',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
     tryjob = tryjob(),
 )
 
 chromiumos_builder(
     name = 'chromeos-kevin-compile-rel',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
     tryjob = tryjob(
         location_regexp = [
@@ -526,7 +521,6 @@ chromiumos_builder(
 
 chromiumos_builder(
     name = 'chromeos-kevin-rel',
-    goma_backend = goma.backend.RBE_PROD,
     goma_enable_ats = True,
     tryjob = tryjob(
         location_regexp = [
@@ -538,18 +532,15 @@ chromiumos_builder(
 
 chromiumos_builder(
     name = 'linux-chromeos-compile-dbg',
-    goma_backend = goma.backend.RBE_PROD,
     tryjob = tryjob(),
 )
 
 chromiumos_builder(
     name = 'linux-chromeos-dbg',
-    goma_backend = goma.backend.RBE_PROD,
 )
 
 chromiumos_builder(
     name = 'linux-chromeos-rel',
-    goma_backend = goma.backend.RBE_PROD,
     goma_jobs = goma.jobs.J150,
     tryjob = tryjob(),
     use_clang_coverage = True,