p-divider: Allow removal of specific dividers

## Pattern to amend

`p-divider`

## Visual
Before:
After:

## Code

```
.p-divider {
.p-divider__block.no-divider {
&::before {
content: none;
}
}
}
```

## Context

Design required a section of p-dividers without the initial divider, [see figma](https://www.figma.com/file/mCV6YajRJtsnEsctbUNgI3/23.10-U.com---Why-Ubuntu-Pro?node-id=168%3A6220&mode=dev). Could also be used to remove any other dividers

Start by locating the p-divider pattern styles and reviewing how its divider elements are generated. Implement the requested way to suppress selected dividers, then verify visually that the initial divider and any other targeted dividers can be removed without affecting the remaining ones.

Written by the indexing model from the issue text.