feat: Query realtime_metrics for low priority selection [NATIVE-203]

[loewenheim]

Follow-up to #28757. should_demote_symbolication will now, in addition to the killswitches, also take into account if a project is registered as low priority in the RealtimeMetricsStore.

As an aside, what's the deal with the project arguments to submit_symbolicate and submit_process? They're never used.

[relaxolotl]

@loewenheim since i was responsible for the conflicts between this branch and master, i've gone in and rebased + cleaned up the conflicts. the only major conflict i've noticed is from the signature change of add_project_to_lpq, and so all of the resolutions i've taken the liberty of patching up are related to that method and the code immediately surrounding it (e.g. add_project_to_lpq).

i've also dropped some linting commits from santrybot which just incorrectly re-introduced dead files, as well as your follow-up commit to fix that linting commit from santrybot.

[relaxolotl]

regarding the project argument: after a bit of spelunking it looks like #14143 changed the contents of submit_process so it no longer relied on the project argument anymore. the original usage of it was to check feature flags on a project.

the params weren't changed in the PR to reflect the removal of all usages of that param, so project is very likely to be vestigial and safe to remove.