Improve contrast with 'ansi-xx-d' console colourisation.

### Jenkins and plugins versions report

Environment

```text
Paste the output here
```

### What Operating System are you using (both controller, and any agents involved in the problem)?

Any OS or browser.

### Reproduction steps

1. Install Pipeline Graph View Plugin.
2. Ensure ANSI Plugin global setting is disabled.
3. Write a Pipeline that outputs ANSI codes, e.g.
```
pipeline {
agent none
options {
ansiColor('xterm')
}
stages {
stage('Color') {
steps {
echo('\033[34mHello\033[0m \033[33mcolorful\033[0m \033[35mworld\033[0m')
}
}
}
}
```
4. Run Pipeline
5. View console text in Pipeline Console.

### Expected Results

Readable text, e.g.

or:

### Actual Results

Text is difficult to read:

### Anything else?

We could look at using similar colours to the Dark Theme:
https://github.com/jenkinsci/dark-theme-plugin/blob/master/src/main/frontend/main.scss

The classes to override are defined in:
https://github.com/jenkinsci/pipeline-graph-view-plugin/blob/main/src/main/frontend/pipeline-console-view/pipeline-console/main/pipeline-console.scss#L92