Unnecessary use of freeze

Summary

# frozen_string_literal: true has been added to files and in the same file the freeze is again being called on the strings.

Example:

In app/model/project.rb,

# frozen_string_literal: true
.
.
.
STATISTICS_ATTRIBUTE = 'repositories_count'.freeze
UNKNOWN_IMPORT_URL = 'http://unknown.git'.freeze

Would like to work on a MR if it is accepted by the team :)