Merge branch 'stable-2.15'

* stable-2.15:
  Update bazlets to latest stable-2.14 to use 2.14.12 API
  Allow access using Basic Authentication prefix
  Update javamelody-core to 1.74.0
  Prefer Javamelody's own configuration constants
  Allow access to metrics from Prometheus
  Migrate `tools/bazel.rc` to `.bazelrc`
  Delegate canMonitor() check to the MonitorFilter
  Update javamelody-core to 1.73.1

Change-Id: I9a79977fd45b9ced002bd9a8b14158f7555ff903