codesearch: Use default service account for codesearch trybots

Bug: 1098927
Change-Id: I1502ff5cea7f38686793695596397beaf3fc92f0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2274959
Auto-Submit: Haiyang Pan <hypan@google.com>
Reviewed-by: Stephen Martinis <martiniss@chromium.org>
Commit-Queue: Haiyang Pan <hypan@google.com>
Cr-Commit-Position: refs/heads/master@{#784162}

infra/config/generated/cr-buildbucket.cfg

@@ -23177,7 +23177,7 @@ buckets {
         path: "win_toolchain"
       }
       build_numbers: YES
-      service_account: "infra-codesearch@chops-service-accounts.iam.gserviceaccont.com"
+      service_account: "chromium-try-builder@chops-service-accounts.iam.gserviceaccount.com"
       task_template_canary_percentage {
         value: 5
       }

infra/config/generated/realms.cfg

@@ -151,7 +151,6 @@ realms {
     role: "role/buildbucket.builderServiceAccount"
     principals: "user:chromium-try-builder@chops-service-accounts.iam.gserviceaccount.com"
     principals: "user:chromium-try-gpu-builder@chops-service-accounts.iam.gserviceaccount.com"
-    principals: "user:infra-codesearch@chops-service-accounts.iam.gserviceaccont.com"
   }
   bindings {
     role: "role/buildbucket.owner"

infra/config/lib/try.star

@@ -338,7 +338,6 @@ def chromium_codesearch_builder(*, name, os=None, **kwargs):
       mastername = 'tryserver.chromium.codesearch',
       goma_backend = builders.goma.backend.RBE_PROD,
       os = os,
-      service_account = "infra-codesearch@chops-service-accounts.iam.gserviceaccont.com",
       **kwargs
   )