chore: Use system.parts table to get count of rows. much cheaper

[fuziontech]

Problem

We are currently doing a huge scan of rows to get counts from clickhouse stats. We really should just query the metadata store for this as it's faster and cheaper...
and less likely to blow out the cache.

Changes

👉 Stay up-to-date with PostHog coding conventions for a smoother review.

How did you test this code?

[github-actions]

Size Change: 0 B

Total Size: 2.01 MB

ℹ️ View Unchanged

Filename	Size
frontend/dist/toolbar.js	2.01 MB

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