Monitor page: apply style to build status legend

[eduardoj]

Is your feature request related to a problem? Please describe.
Some style changes were applied on build status in the monitor page. It would be nice to apply the same styles in the legend.

Describe the solution you'd like
Use the same styles in the legend than in the table, for describing each build status.

Describe alternatives you've considered
None.

Additional context
One of the last pull request regarding these style changes: #8170.

[darix]

👍

[hennevogel]

LGTM

[eduardoj]

Making things more clear, by providing an example:

• the string "succeeded" shows itself with a green font in the monitor page
• the purpose of the issue is showing the "succeded" string with a green font in the build status legend.

And the same for the rest of the elements of the legend.