Remove outstanding references to buck

Most references are in documentation and comments. The main
developer-visible behavior change is moving the downloaded artifact
cache from ~/.gerritcodereview/buck-cache to bazel-cache, which will
result in re-downloading dependencies on the next build; this had to
happen sooner or later. Alternatives, which are not worth the effort,
include teaching the scripts to accept both locations, or having it
rearrange and/or symlink directories behind the scenes.

There are just a few references remaining, all of which are intentional:

$ git grep -Pi '\bbuck(lets?)?\b' HEAD
HEAD:java/com/google/gerrit/httpd/raw/StaticModule.java:        // https://gerrit-review.googlesource.com/#/c/57570/57/gerrit-httpd/BUCK@32
HEAD:resources/com/google/gerrit/server/mime/mime-types.properties:bucklet = text/x-python
HEAD:resources/com/google/gerrit/server/mime/mime-types.properties:BUCK = text/x-python

Change-Id: Idb93a483451ccf86ba96c379d38008a7894c3f95
diff --git a/Documentation/dev-release-subproject.txt b/Documentation/dev-release-subproject.txt
index fcafea5..4886849 100644
--- a/Documentation/dev-release-subproject.txt
+++ b/Documentation/dev-release-subproject.txt
@@ -32,7 +32,7 @@
 ----
 
 * Change the `id`, `bin_sha1`, and `src_sha1` values in the `maven_jar`
-for the subproject in `/lib/BUCK` to the `SNAPSHOT` version.
+for the subproject in `/WORKSPACE` to the `SNAPSHOT` version.
 +
 When Gerrit gets released, a release of the subproject has to be done
 and Gerrit has to reference the released subproject version.