Box shadow for gl-link items in the nav should be outline instead

The following discussion from !74551 (merged) should be addressed:

• @dstull started a discussion: (+6 comments)

  @kcomoli since you designed this one from what I can see in #213376[Trial_status_1st_steps.jpg]

  Can you give the change of styling of what happens on focus/hover as described in the screenshots a review?