Automatically prune unused Go dependencies

The way gazelle was set up meant that it would never prune any
dependencies from go_deps.bzl. I'm not exactly sure _why_, but that's
the way it behaved.

The new approach here in this patch is to essentially null out
go_deps.bzl and have gazelle regenerate it from scratch.

Signed-off-by: Philipp Schrader <philipp.schrader@gmail.com>
Change-Id: Ic94020df816afa0df798b19b16b11272579793be
diff --git a/tools/lint/BUILD b/tools/lint/BUILD
index d33d786..8d9b150 100644
--- a/tools/lint/BUILD
+++ b/tools/lint/BUILD
@@ -32,6 +32,7 @@
         ":buildifier",
         ":gofmt",
         "//:gazelle-runner",
+        "//tools/go:mirror_go_repos",
         "//tools/go:tweak_gazelle_go_deps",
         "@go_sdk//:bin/go",
     ],