Add environment variables to support bundle

[dehaansa]

PR Description

Update the support bundle to collect relevant Golang runtime environment variables.

relevantVariables := []string{
	"AUTOMEMLIMIT",
	"GODEBUG",
	"GOEXPERIMENT",
	"GOGC",
	"GOMAXPROCS",
	"GOMEMLIMIT",
	"HOSTNAME",
	"HTTP_PROXY",
	"HTTPS_PROXY",
	"PPROF_BLOCK_PROFILING_RATE",
	"PPROF_MUTEX_PROFILING_PERCENT",
}

Which issue(s) this PR fixes

#2067

PR Checklist

• CHANGELOG.md updated
• Documentation added

[clayton-cornell]

Do we need to add these env vars to: https://grafana.com/docs/alloy/latest/reference/cli/environment-variables/

[dehaansa]

There's definitely value to add GOGC, HTTPS_PROXY, GOMAXPROCS documentation. AUTOMEMLIMIT is also worth documenting though it's specific to a module that we use, rather than the go runtime itself.

In reviewing documentation I could find elsewhere GOEXPERIMENT is probably not relevant, looks like that's only used at build time so I'll remove that from this PR.