Revert "Add rake task to gather `GC.stat` for Sidekiq."

This reverts commit 15e2f55655.

lib/tasks/gc.rake

@@ -1,21 +0,0 @@
-desc "Returns `GC.stat` for each Sidekiq process in JSON"
-task "sidekiq:gc_stat" do
-  pids = `ps -eo pid,args | grep ' [s]idekiq ' | awk '{print $1}'`.split("\n").map(&:to_i)
-  results = []
-  hostname = `hostname`.chomp
-
-  pids.each do |pid|
-    tmp_path = Tempfile.new.path
-
-    system(
-      "bundle exec rbtrace -p #{pid} -e \"o = GC.stat; f = File.open('#{tmp_path}', 'w'); f.write(o.to_json); f.close\"",
-      out: "/dev/null", err: "/dev/null"
-    )
-
-    result = JSON.parse(File.read(tmp_path))
-    result["hostname"] = hostname
-    results << result
-  end
-
-  puts results.to_json
-end