Add post deploy migration to remove open_project_data

What does this MR do and why?

Adds the post deploy migration to remove the open_project_data table as part of this MR for this issue

Migration

$ rake db:migrate
== 20210923192648 RemoveForeignKeysFromOpenProjectDataTable: migrating ========
-- transaction_open?()
   -> 0.0000s
-- remove_foreign_key(:open_project_tracker_data, {:column=>:service_id})
   -> 0.0090s
== 20210923192648 RemoveForeignKeysFromOpenProjectDataTable: migrated (0.0294s)

== 20210923192649 RemoveOpenProjectDataTable: migrating =======================
-- drop_table(:open_project_tracker_data)
   -> 0.0040s
== 20210923192649 RemoveOpenProjectDataTable: migrated (0.0041s) ==============

$ rake db:migrate:down VERSION=20210923192649
== 20210923192649 RemoveOpenProjectDataTable: reverting =======================
-- create_table(:open_project_tracker_data, {})
   -> 0.0090s
== 20210923192649 RemoveOpenProjectDataTable: reverted (0.0091s) ==============

$ rake db:migrate:down VERSION=20210923192648
== 20210923192648 RemoveForeignKeysFromOpenProjectDataTable: reverting ========
-- transaction_open?()
   -> 0.0000s
-- add_foreign_key(:open_project_tracker_data, :integrations, {:column=>:service_id, :on_delete=>:cascade})
   -> 0.0051s
== 20210923192648 RemoveForeignKeysFromOpenProjectDataTable: reverted (0.0279s)

Related to #330832 (closed).

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• I have evaluated the MR acceptance checklist for this MR.