Remove `<br>` tags and other styling elements from inside `<Trans>` tags

[sraby]

As @toolness brings up, having formatting/styling elements rather than content inside snippets to translate has the potential to confuse translators (especially since they can't see the actual type of tag). We should think of ways to fix this.

Originally brought up in https://github.com/JustFixNYC/tenants2/pull/1405#discussion_r421811692.