codeintel: add dashboard for precide-code-intel-worker total in-progress upload size

Created by: Strum355

Introduces a new panel in the precise-code-intel-worker dashboard for tracking the total in-progress uploads per-instance. This may help us in tracking correlation between in-progress uploads' size and resource usage for better instance sizing.

Follows on from @rafax: I think the guidance was "precise-code-intel-worker needs more than 3x the size of largest LSIF upload", but we don't have a metric that shows the size of attempted uploads - adding a metric for this would be useful.

Test plan

Tested locally, see picture:

TODO: see if theres any unit tests we can add