Adds a few UX tweaks after a call with @andyvolpe

What does this MR do?

Adds a few UX tweaks after a call with @andyvolpe

• 8px margins between vulnerability action buttons
• Sentence casing fixes on various parts of the dashboard
• Phrasing alignment between the action buttons and modal (dashboard)
• Renamed "Undo Dismissal" to "Revert Dismissal" (see above)
• Fixed the "more info" button color

What are the relevant issue numbers?

#6709 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• EE specific content should be in the top level /ee folder
• For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?