vm-builder: Turn off --auto-discover-databases

[ololobus]

It causes exporter connection to every database in the Postgres and it was disabled for pods a while ago, but I forgot that VMs have a different build path.

See this for details:
https://github.com/neondatabase/cloud/commit/0a60057f3380e570b540cc823975e07400cd640c

Also remove --exclude-databases it seems to be bogus as well, see:
prometheus-community/postgres_exporter#588

[ololobus]

Hm, looks like one of the tests fails (seems to be related to live migration no, migration passed, but autoscaling test failed)

Finished	Migration finished with success to target pod (example-dvcr5)		
    logger.go:42: 15:48:53 | vm-migration | Deleting namespace: kuttl-test-golden-coral
=== CONT  kuttl
    harness.go:405: run tests finished
    harness.go:513: cleaning up
    harness.go:570: removing temp folder: ""
--- FAIL: kuttl (369.85s)
    --- FAIL: kuttl/harness (0.00s)
        --- FAIL: kuttl/harness/autoscaling (338.96s)
        --- PASS: kuttl/harness/vm-migration (29.97s)
FAIL
make: *** [Makefile:365: e2e] Error 1

https://github.com/neondatabase/autoscaling/actions/runs/6574880494/job/17862265473?pr=571#step:15:218

But I don't get what the error is. @sharnoff can you please help with reading this test result?

[sharnoff]

Looks like downscale is failing because the vm-monitor is hitting internal errors. Unfortunately we don't have logs for the VMs themselves, but it's unlikely that it's failing because of this PR — each vm-monitor is pulled from neondatabase/neon's current main, so maybe some recent change or something.

I'll dig into it further.

[ololobus]

OK, I'd avoid stacking PR on top of failing tests and it's not urgent, so let me know when it makes sense to re-run / safe to merge

[sharnoff]

Problem was fixed with neondatabase/neon#5606, all good to merge.

[sharnoff]

Filed #577 to track the long term solution for moving postgres_exporter configuration into the control plane (among other things).

There's more immediate changes that could be made to make that simpler, if we anticipate needing to do this frequently or with urgency.