Upgrade bazlets to latest stable-2.15 to build with 2.15.10 API
Upgrade bazlets to latest stable-2.15 to build with 2.15.10 API

Change-Id: I6a25d60bf8b055bc34acfc09f94b1fcfda5a7ebb

GerritCodeReview/plugins_javamelody,GerritCodeReview/plugins_javamelody,GerritCodeReview/plugins_javamelody