Remove title and description columns from services table

What does this MR do?

After removing and ignoring the title and description columns from the code in !33298 (merged), we can now drop the database columns.

Migration script output

$ rails db:migrate
== 20200727114147 RemoveTitleAndDescriptionFromServices: migrating ============
-- remove_column(:services, :title, :string)
   -> 0.0011s
-- remove_column(:services, :description, :string, {:limit=>500})
   -> 0.0002s
== 20200727114147 RemoveTitleAndDescriptionFromServices: migrated (0.0015s) ===

$ rails db:rollback
== 20200727114147 RemoveTitleAndDescriptionFromServices: reverting ============
-- add_column(:services, :description, :string, {:limit=>500})
   -> 0.0013s
-- add_column(:services, :title, :string)
   -> 0.0003s
== 20200727114147 RemoveTitleAndDescriptionFromServices: reverted (0.0039s) ===

Related to #217587 (closed)