Reapply table-layout fixed in repository file list

What does this MR do and why?

A. In this recently merged MR > !69445 (merged), we removed the table-layout: fixed to solve this problem.

B. However, this class needed to prevent CLS (Cummulative Layout Shift) -- notice the column shift 😱

before

So, in this MR, we re-apply the table-layout: fixed. BUT we only added it for the file list that doesn't contain ... as the first row.

Reapply "gl-table-layout-fixed"	Leave out "gl-table-layout-fixed"

Follow up Issue

HOWEVER! by removing the table-layout: fixed, our CLS does return 😓. So we should explore how to address this for file list with directories. Let's solve this iteratively and fix it in a follow-up. At least with this MR fix we don't have CLS for files list that doesn't contain ....

If you're wondering why table-layout: fixed won't work for files with ... > #341851 (closed)

This causes invalid columns widths on mobile devices because table-layout: fixed calculates widths just once using the first available row which is the row with the button Go up.

#341876

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Related to #341851 (closed)