Don't blindly mark flash strings HTML safe
Don't blindly mark flash strings HTML safe

This is in partial fulfillment of #3228.

Removing the `#html_safe` calls from this line avoids marking arbitrary strings
as safe when they are very likely not.

Providers of flash messages need to be refactored to manage the safety of the
buffers they provide.

samvera/hyrax,samvera/hyrax,samvera/hyrax,samvera/hyrax