Use commons-io from Gerrit plugin API

commons-io is now provided by Gerrit itself and included in
release.war. Consume it from the Gerrit plugin API and stop shading it
into the delete-project plugin.

Depends-On: https://gerrit-review.googlesource.com/c/gerrit/+/549767
Change-Id: I6f8bad63d5cbaab21bc731b8ba6929c35ba6992c

BUILD

diff --git a/BUILD b/BUILD
index 1f7aabb..1bfb09a 100644
--- a/BUILD
+++ b/BUILD
@@ -18,7 +18,6 @@
     ],
     resource_jars = ["//plugins/delete-project/web:gr-delete-repo"],
     resources = glob(["src/main/resources/Documentation/*.md"]),
-    deps = ["@commons-io//jar"],
 )
 
 junit_tests(
@@ -36,7 +35,6 @@
     visibility = ["//visibility:public"],
     exports = PLUGIN_DEPS + PLUGIN_TEST_DEPS + [
         ":delete-project__plugin",
-        "@commons-io//jar",
         "@mockito//jar",
     ],
 )