Inconsistent tooltips appearance and behaviours

Tooltips throughout the UI have inconsistent styles, and are often misplaced.

Examples:

## Acceptance criteria

- The _connector_ of the tooltip to the content, which is currently a very subtle arrow, is removed — the effort to improve its visibility and positioning behaviour adds very little value.
- Some tooltips are either improved, or removed. For example, the above tooltip beside "Identity Overrides" has very similar text to what's already in the blue note below it.
- Styles are consistent: regular `font-weight`, reasonable `line-height`, and proper spacing around and between paragraphs — we have multiple sometimes.