Fix old unique jobs digests not having been cleaned up (#13683)

db/migrate/20200508212852_reset_unique_jobs_locks.rb

@@ -0,0 +1,12 @@
+class ResetUniqueJobsLocks < ActiveRecord::Migration[5.2]
+  disable_ddl_transaction!
+
+  def up
+    # We do this to clean up unique job digests that were not properly
+    # disposed of prior to https://github.com/tootsuite/mastodon/pull/13361
+
+    SidekiqUniqueJobs::Digests.delete_by_pattern('*', count: SidekiqUniqueJobs::Digests.count)
+  end
+
+  def down; end
+end