build: remove unused build job (#29299)

.circleci/config.yml

@@ -1671,19 +1671,6 @@ jobs:
     <<: *steps-electron-ts-compile-for-doc-change
 
   # Layer 1: Checkout.
-  linux-checkout:
-    executor: linux-docker
-    environment:
-      <<: *env-linux-2xlarge
-      GCLIENT_EXTRA_ARGS: '--custom-var=checkout_arm=True --custom-var=checkout_arm64=True'
-    steps:
-      - electron-build:
-          persist: false
-          build: false
-          checkout: true
-          persist-checkout: true
-          restore-src-cache: false
-
   linux-checkout-for-workspace:
     executor: linux-docker
     environment: