Remove unused and potentially risky `srText` from VBrand component

[sarayourfriend]

Problem

The VBrand component has a prop called srText that a) allows you to change the text the screen reader would read for the Openverse logo and brand mark and b) has documentation that suggests we might one day set the text to empty.

1. When would we ever want to set it to empty? Wouldn't that be an a11y issue?
2. Under what circumstances do we need to be able to change this?

Generally my sense about this is YAGNI. The prop seems risky to me (and the documentation potentially gives bad advice, I'm not sure) and we don't use it anywhere.

Is there a specifically planned usage for this prop @WordPress/openverse-frontend?

Implementation

• [ ] 🙋 I would be interested in implementing this feature.