Changed dashed border button color to be darker

What does this MR do?

Changed the border color of dashed border buttons to be darker.

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Why was this MR needed?

Dashing the border, makes the border thinner, aside from leaving gaps. This creates the optimal illusion that the border color is not the same. To remove that effect, we have to darken the border to make up for the extra whiteness. This makes those buttons discoverable again.

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Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

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