Precompile out of env deps in serial within precompilepkgs

[IanButterworth]

Fixes #59121

Brings serial precompilation jobs into the parallel precompilation job, so users don't have to hit the old error-looking serial log path.

These jobs will likely take longer because they may be precompiling their deps internally, so the (serial) label has been added.

Master

PR

Todo

• Explain what (serial) means in the docs

[IanButterworth]

One thing that needs figuring out here is that the previous [Info : Precompiling logs were hidden @debugs on non-interactive mode. But Base.precompilepkgs always prints to stderr (unless there's nothing to be done).

So there are some tests that actually precompile packages that are being tripped up that monitor stderr.

I'm not sure whether to fix tests here, or restore that hidden precompilation behavior..

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I opted to keep it printing to stderr in noninteractive mode too and fix tests. I think its ok to print this stuff to stderr.

[topolarity]

the (serial) label has been added.

Should this be labelled (non-parallel) or (single-process)?

And should it be attached to the Precompiling... prompt, instead of individual packages?

I worry that (serial) is only obvious if you've already been taught what "serial pre-compilation" means - One might walk away with the impression that this is compiling a customized version of the package (esp. since that's what, e.g., gray -O3 text in the same spot means)

[IanButterworth]

(non-parallel) SGTM