Enable build step for RBE presubmit

I noticed that we have only been running the test step for the RBE presubmit. This also enables the building of the Bazel binary.

RELNOTES: None
PiperOrigin-RevId: 258767691
diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml
index 3b81a52..13f68b9 100644
--- a/.bazelci/presubmit.yml
+++ b/.bazelci/presubmit.yml
@@ -322,6 +322,16 @@
     - sed -i.bak -e 's/^# android_sdk_repository/android_sdk_repository/' -e 's/^#
       android_ndk_repository/android_ndk_repository/' WORKSPACE
     - rm -f WORKSPACE.bak
+    build_flags:
+    - "--config=ubuntu1604_java8"
+    - "--remote_executor=grpcs://remotebuildexecution.googleapis.com"
+    - "--jobs=200"
+    - "--experimental_remote_download_outputs=minimal"
+    - "--experimental_inmemory_jdeps_files"
+    - "--experimental_inmemory_dotd_files"
+    build_targets:
+      - "//src:bazel"
+      - "//src:bazel_jdk_minimal"
     test_flags:
     - "--config=ubuntu1604_java8"
     - "--remote_executor=grpcs://remotebuildexecution.googleapis.com"