Deprecate and ignore gtk-entry-password-hint-timeout

Deprecate and ignore gtk-entry-password-hint-timeout

This feature offers a number of benefits related to providing
feedback to the user when the password is masked. Some experts have
argued that password masking is harmful. I tend to agree with this
setting providing a better and more moderate solution. Some agree:
https://www.schneier.com/blog/archives/2009/07/the_pros_and_co.html

In order to further lessen the impact I've only enabled the feature
on the primary display since the likelyhood of a non-primary display
being visible by others is higher.