vector: Do styles the ResourceLoader way

It used to be done like this a few releases ago, but went
through some perturbation when the LESS rewrite happened
and afterwards during beta-testing the typography refresh.

The current way causes enough issues that I think the gain
from getting rid of it is worth losing some brevity.

Bug: 56592
Change-Id: Ibeff450fad789fbc67d95a1a9befd315f7405421
(cherry picked from commit e4f973bd4c6bb0b9c4d0d210fde18ec73c11aee4)