Set JVM version before running GJF

GJF is a Java executable that needs a specific JVM version
to run. Failing to set the correct JVM would result in the
failure of the formatting check.

Change-Id: Iae58d9227f010e03b03de7fa489cea7ec9f2737e

jenkins/gerrit-codestyle-gjf.sh

diff --git a/jenkins/gerrit-codestyle-gjf.sh b/jenkins/gerrit-codestyle-gjf.sh
index c116051..7c00fff 100644
--- a/jenkins/gerrit-codestyle-gjf.sh
+++ b/jenkins/gerrit-codestyle-gjf.sh
@@ -38,4 +38,5 @@
 fi
 
 echo 'Running google-java-format check...'
+. set-java.sh --branch "$TARGET_BRANCH"
 git show --diff-filter=AM --name-only --pretty="" HEAD | grep java$ | xargs -r $GJF -n --set-exit-if-changed