Revert "Preparations for hiding username/password/submit inputs on login page."

This reverts commit 4bde2f77add3f24bb36f0601d8942b6fee127879.
Revert "Fix this: https://github.com/datagovuk/dgu_d7/issues/440"

This reverts commit 6865a8952e6fd7a4492ffecdb63cbc25ec2d4fab.
Revert "Realnemt under modules/custom"

This reverts commit 593cc24aaeb111653763605ebda533f0bed3f158.