Disable livenessprobe by default

[friedrichg]

I have run all cortex components for years without liveness probes.
they are bad for store-gateways because it causes re-sharding if they are under pressure.
Restarting store-gateways can take a long time to recover, same for others components.
We should disable all of them by default and let users enable them as needed.

Similar to
#263

[friedrichg]

Also bad for compactors as confirmed today

[aep]

they also seem to be designed wrong?

the ready endpoint for store-gateway returns

Some services are not Running:
Running: 3
Starting: 1

so store-gateway is being killed because some other service isnt ready,
but the other service doesnt have a probe?

[nschad]

+1

We should just remove it.

@friedrichg

Should we just drop livenessProbe for store-gateway and compactor then?

[friedrichg]

@nschad yes, please

[nschad]

Sorry for the hold-up

PR is open #502

@friedrichg