[kube-prometheus-stack] Enable affinity specification for node exporter

[frvasquezjaquez]

Is your feature request related to a problem? Please describe.
I have an AWS cluster with EC2 and fargate nodes. When i deploy the prometheus stack chart it tries to deploy a node exporter daemon set in all the nodes, even in fargate nodes, which are serverless, so it causes that some pods stay Pending.

Describe the solution you'd like
Add the node selector or affinity tag to the value.yml so i can especify in which nodes i want to deploy the node exporters.

Additional context

1. This is the error that im getting in the fargate nodes:

0/8 nodes are available: 3 Too many pods, 5 node(s) didn't have free ports for the requested pod ports.

2. This is the affinitt created automatically by the helm chart:

nodeAffinity:
  requiredDuringSchedulingIgnoredDuringExecution:
    nodeSelectorTerms:
      - matchFields:
          - key: metadata.name
            operator: In
            values:
              - fargate-ip-xxx.xxxx.xxx.xxx.ec2.internal

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Any further update will cause the issue/pull request to no longer be considered stale. Thank you for your contributions.

[xpunch]

affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
              - matchExpressions:
                  - key: eks.amazonaws.com/compute-type
                    operator: NotIn
                    values:
                      - fargate

[frvasquezjaquez]

Excellent, thanks!