Improve accessibility of gray color CI status icons

What does this MR do?

Darken gray icons in pipeline status icon

This fix darkens inaccessible pipeline status icon colors in MR widget and mini-pipeline graph.

It also fixes inconsistency between preparing and created statuses.

• Add screenshots of result in different places
• Test in dark mode

Screenshots (strongly suggested)

In order of state "normal", "hover", "active":

	minipipeline	icon
normal
darkmode

In MR Widget

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #283897 (closed)