Rename the filter by_confidentiality to by_project_confidentiality and by_authorization to by_project_authorization

Rename the filter by_confidentiality to by_project_confidentiality and by_authorization to by_project_authorization in ee/lib/search/elastic/filters.rb

Implementation Guide

• Find the usage of the by_confidentiality in the code and rename all the occurences with by_project_confidentiality (it is mostly in ee/lib/search/elastic/issue_query_builder.rb, ee/lib/search/elastic/work_item_query_builder.rb and ee/spec/lib/search/elastic/filters_spec.rb)
• Do the same for by_authorization it is also in the same places.