Positive indication in logs whether GOMEMLIMIT was set.

[Jaypers]

Is your proposal related to a problem?

Although there is a negative indication when --enable-auto-gomemlimit fails to set the GOMEMLIMIT
i.e. "Failed to set GOMEMLIMIT automatically"
there is no way to see if GOMEMLIMIT was set and set correctly.

Describe the solution you'd like

For Thanos to print something in the logs (or debug logs) to indicate that the limit was set and what exactly it was set to.

e.g.:
GOMEMLIMIT set to 2147483648 bytes, 90% of pod memory limit.
or
GOMEMLIMIT set to 2147483648 bytes, 90% of detected memory.

Describe alternatives you've considered

Go debugger

Additional context

It seems that our compactors are not honouring --enable-auto-gomemlimit running on ARM images.

[Jaypers]

This would be similar to GOMAXPROCS e.g.:
caller=main.go:77 level=debug msg="maxprocs: Updating GOMAXPROCS=2: determined from CPU quota"