Use proper functions for escaped translations.

pros jcastaneda.
fixes #30012.
Built from https://develop.svn.wordpress.org/trunk@29961


git-svn-id: http://core.svn.wordpress.org/trunk@29708 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Move password hint text to a function. Add 'password_hint' filter.

props convissor.
fixes #21243.
Built from https://develop.svn.wordpress.org/trunk@29962


git-svn-id: http://core.svn.wordpress.org/trunk@29709 1a063a9b-81f0-0310-95a4-ce76da25c4cd