Use Java 11 in GCB to build release candidates (#736)

release/cloudbuild-kythe.yaml

@@ -14,7 +14,7 @@
 # https://cloud.google.com/cloud-build/docs/running-builds/automate-builds
 steps:
 # Download Kythe
-- name: 'openjdk:11'
+- name: 'gcr.io/${PROJECT_ID}/builder:latest'
   entrypoint: /bin/bash
   args:
   - -c
@@ -25,7 +25,7 @@ steps:
     rm kythe-${_KYTHE_VERSION}.tar.gz
     mv kythe-${_KYTHE_VERSION} kythe
 # Build Nomulus with the Kythe wrapper
-- name: 'openjdk:11'
+- name: 'gcr.io/${PROJECT_ID}/builder:latest'
   entrypoint: /bin/bash
   args:
   - -c
@@ -40,7 +40,7 @@ steps:
     ./gradlew clean testClasses -x compileProdJS \
       -Dno_werror=true -PenableCrossReferencing=true
 # Merge kzip files
-- name: 'openjdk:11'
+- name: 'gcr.io/${PROJECT_ID}/builder:latest'
   entrypoint: /bin/bash
   args:
   - -c