Update bazlets to latest revision on stable-2.15

- Adjust names of prolog dependencies
- Add optional dir_name argument to gerrit_plugin
- gerrit_plugin: Improve stamping error message
- Upgrade Gerrit API to version 2.15.2
- Set Gerrit API snapshot version to 2.15.2-SNAPSHOT
- Fix the error in project properties generation file
- Switch to 2.14.9-SNAPSHOT Gerrit API version for local dev
- Fix deletion of Sonar Scanner folder
- Automate SonarQube analysis for plugins built with bazel
- Use bazel-cache instead of buck-cache
- Use bazel-cache instead of buck-cache
- Update Gerrit API to 2.14.8
- Set Gerrit API snapshot version to 2.14.8-SNAPSHOT

Change-Id: I3a6999700696e71084710a66e7829b0630fa3190

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 6f890c6..1cba3d1 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "1419057b24e41cda9a6ee9d9c431b9005faf8190",
+    commit = "7ce9a3f58f030635b3a1229b7fb4c62ee7979bc8",
     # local_path = "/home/<user>/projects/bazlets",
 )