## Problem
`test_compute_startup_simple` and `test_compute_ondemand_slru_startup`
are failing.
This test implicitly asserts that the metrics.json endpoint succeeds and
returns all expected metrics, but doesn't make it easy to see what went
wrong if it doesn't (e.g. in this failure
https://neon-github-public-dev.s3.amazonaws.com/reports/main/14513210240/index.html#suites/13d8e764c394daadbad415a08454c04e/b0f92a86b2ed309f/)
In this case, it was failing because of a missing auth token, because it
was using `requests` directly instead of using the endpoint http client
type.
## Summary of changes
- Use endpoint http wrapper to get raise_for_status & auth token
## Problem
`TYPE_CHECKING` is used inconsistently across Python tests.
## Summary of changes
- Update `ruff`: 0.7.0 -> 0.11.2
- Enable TC (flake8-type-checking):
https://docs.astral.sh/ruff/rules/#flake8-type-checking-tc
- (auto)fix all new issues
## Problem
We had a recent Postgres startup latency (`start_postgres_ms`)
degradation, but it was only caught with SLO alerts. There was actually
an existing test for the same purpose -- `start_postgres_ms`, but it's
doing only two starts, so it's a bit noisy.
## Summary of changes
Add new compute startup latency test that does 100 iterations and
reports p50, p90 and p99 latencies.
Part of https://github.com/neondatabase/cloud/issues/24882
