Accessibility: Fix footer issues

Created by: umpox

Description

Issue 1: Footer wasn't fully readable on 320px. Fix is pretty minor but makes it readable.

BEFORE	AFTER

Issue 2: Alt text was unnecessary on DevTools time logo (repeated)

Test plan

1. Run locally with a screen reader/mobile screen

Closes https://github.com/sourcegraph/sourcegraph/issues/34412

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.