Revert "Updates Stackdriver Debugger to 3.x line, before deprecation"

Author: pivotal-david-osullivan

config/google_stackdriver_debugger.yml

@@ -15,7 +15,7 @@
 
 # Configuration for the Groovy container
 ---
-version: 3.+
+version: 2.+
 repository_root: "{default.repository.root}/google-stackdriver-debugger/{platform}/{architecture}"
 application_name: 
 application_version: