Make "Space Used" gray instead of green in multisite Right Now box.

[jane]

Multisite adds:

Storage Space
100MB Space Allowed 0MB (0%) Space Used

...and "Space Used" is green by default. It should be gray since it doesn't denote an action has applied a positive status. Gray until the 'almost near limit' color kicks in.

[ocean90]

First one is for grey -> orange (<=40%) -> red (>=70%), second one for grey -> red (>=70%).

[ryan]

In [17799]:

Make "Space Used" gray instead of green in multisite Right Now box. Props ocean90. fixes #17283