goroutinedumper: Compress files

[bdarnell]

Goroutine dumps are large, but compress well. With default settings, the goroutine dumper will fire when there are 1000 goroutines, which produces a file of about 9MB that gzips down to 500KB. We should compress the files we write here (and probably reduce the total_dump_size_limit - spending half a gig on this is kind of silly when we only budget 100MB for logs in util/log).

I'm noticing this because #35986 produces 400MB of goroutine dumps per run (twice the size of its log files), so stressing it keeps filling up my local disk.

[tbg]

@giorgosp -- if you're interested in knocking out another issue, this one would be a good follow-up to #36813. Basically in this code

cockroach/pkg/server/goroutinedumper/goroutinedumper.go

Lines 177 to 188 in 4dcde30

	func takeGoroutineDump(dir string, filename string) error {
	path := filepath.Join(dir, filename)
	f, err := os.Create(path)
	if err != nil {
	return errors.Wrapf(err, "error creating file %s for goroutine dump", path)
	}
	defer f.Close()
	if err = pprof.Lookup("goroutine").WriteTo(f, 2); err != nil {
	return errors.Wrapf(err, "error writing goroutine dump to %s", path)
	}
	return nil
	}

we wouldn't pass f to WriteTo, but we'd wrap f it in a gzip.NewWriter, and perform the necessary cosmetics (i.e. chose a filename ending in .txt.gz, adapt debug zip to use a .txt.gz ending as well). I think the GetFiles endpoint would just return the compressed files, which is what we want.