WIP, needs larger migration: go 1.24 changes

[Groxx]

High level stuff changed:

• All go.mod and docker stuff points to 1.24
• go list has made significant changes to what is allowed yet again, so check-gomod-version.sh has major changes, but does the same thing
• Minor makefile fixes and ensuring go-generate checks versions before misbehaving
  • This is mostly unnecessary until a golang.org/x/tools check is in place, but it's a bit beneficial either way
• 1.24 cleanup for timer.Stop() draining
• Upgraded golang.org/x/tools to v0.32.0 to match our internal repos, needed to parse newer libraries / code supported by go 1.24

... and then got stuck on mockery.

We essentially have two options:

1. migrate to mockery v3
2. leave mockery, move its mocks over to mockgen

2 seems like it might be much easier, but 1 is worth considering at some point at least.

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Mockery-v2 is not compatible with go 1.24, and v3 has fixed that. Unfortunately, mockery-v3 drops support for our go generate-command-line-flags entirely, and forces us to switch to their config files.

AFAICT that's a good change, and it should let us speed up code generation a lot (by running them as a dedicated pass, rather than in go generate). But it's non-trivial so I've stopped here.

There's a migration guide for whenever someone feels like tackling it: https://vektra.github.io/mockery/v3.5/v3/ We might even consider replacing gowrap with it tbh, it looks like it might be a pretty powerful code generator framework.