Fix bad spacing in topic title on monobook

Best practices[1] encourage using unitless line height, specifying 
line-height with em's inherits differently causing rendering errors
such as the topic title in monobook.  I reviewed all the places these
are used in with both monobook and vector.  There are some tiny changes
in line height removing the em's but it generally looks the same.

Note that some of these locations aren't actually used. 
navagiation.less is unreferenced from the templates.  forms.less has
a few line-height definitions, but only the first for 
.mw-ui-input-large is used(for the nojs new topic link). The others are
referenced from form_element.handlebars but that template is never
called either.

[1] https://developer.mozilla.org/en-US/docs/Web/CSS/line-height#Prefer_unitless_numbers_for_line-height_values

Bug: T76602
Change-Id: I00007404dea26ec1cf2a42c45dec93ce126cb4a9
Merge "Fix bad spacing in topic title on monobook"