chore: log in to DockerHub during the main build (#9839)

Similarly like we added for the PR build in #9809.

----

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buildspec.yaml

@@ -8,6 +8,8 @@ phases:
       # Start docker daemon inside the container
       - nohup /usr/bin/dockerd --host=unix:///var/run/docker.sock --host=tcp://127.0.0.1:2375 --storage-driver=overlay2&
       - timeout 15 sh -c "until docker info; do echo .; sleep 1; done"
+      # login to DockerHub to avoid throttling
+      - docker login -u ${DOCKERHUB_USERNAME} -p ${DOCKERHUB_PASSWORD}
 
       # Install yarn if it wasn't already present in the image
       - yarn --version || npm -g install yarn
@@ -29,4 +31,4 @@ reports:
   jest-tests:
     files:
       - "**/junit.xml"
-    file-format: JunitXml
+    file-format: JunitXml