Fix security scanning loading states

This is an actionable insight from the UX Department: MRs experience async critique research (insight).

In the merge request widget, when using security scanning features, the loading states are inconsistent and can raise questions:


	Is something loading or did it not load correctly?
	There's a loading icon and a `(is loading)` in parentheses.
	Here "is loading" is part of the statement, above it's in parenthesis, any reason why?

These UI text issues impact the sense of trust that users place on the product.

Fix the inconsistencies across all loading states of the security widgets.