Fixed #7245 Inconsistent output from ActiveSupport::TimeZone.all

Now this is not given any inconsistent out.

ActiveSupport::TimeZone.all
chicago = ActiveSupport::TimeZone['America/Chicago']
ActiveSupport::TimeZone.all.include?(chicago)
=> false

chicago = ActiveSupport::TimeZone['America/Chicago']
ActiveSupport::TimeZone.all.include?(chicago)
=> false

This fixes #7245