Only embed single chart in Plan:Project Management BE page

Having the full dashboard embedded isn't useful or necessary:

1. While we say that team members aren't evaluated on this, that's context that not everyone viewing the handbook will have, or they might not use in the same way.
2. The more of the dashboard we include, the harder it is to actually use because the handbook page is quite narrow.
3. The more of the dashboard we include, the longer the page takes to load.

The most relevant information here is against the MRs per engineer target. By embedding just this chart, the filters are unavailable in the handbook too, so we can solve all the problems at once.