Add global.affinity parameter to mimir-distributed helm chart

[roman-k3i]

Description

My concern so far is that I need to set up all pods required by helm charts on specific nodes with labels.
To achieve this, I need to set the affinity for each particular pod that exists in the helm chart.
It would simplify if it would be possible to set it as a global parameter

What expectation

A parameter global.affinity in the mimir-distributed helm chart allows it to be set for all pods.