chore(release): Switch to Ruby-based release reporter (#208)

Author: dazuma

.kokoro/release.sh

@@ -8,6 +8,4 @@ export GEM_HOME=$HOME/.gem
 export PATH=$GEM_HOME/bin:$PATH
 
 gem install --no-document toys
-toys release install-python-tools -v
-python3 -m releasetool publish-reporter-script > /tmp/publisher-script; source /tmp/publisher-script
-toys release perform -v --enable-docs < /dev/null
+toys release perform -v --reporter-org=googlecloudplatform --enable-docs < /dev/null