Jsonnet: allow to not configure topologySpreadConstraints at all

[pracucci]

What this PR does

Allow to not configure topologySpreadConstraints by setting the following configuration options to a negative value:

• distributor_topology_spread_max_skew
• query_frontend_topology_spread_max_skew
• querier_topology_spread_max_skew
• ruler_topology_spread_max_skew
• ruler_querier_topology_spread_max_skew

diff /Users/marco/workspace/src/github.com/grafana/mimir/operations/mimir-tests/test-all-components-generated.yaml /Users/marco/workspace/src/github.com/grafana/mimir/operations/mimir-tests/test-all-components-without-pod-topology-constraints-generated.yaml

563,569d562
<       topologySpreadConstraints:
<       - labelSelector:
<           matchLabels:
<             name: distributor
<         maxSkew: 1
<         topologyKey: kubernetes.io/hostname
<         whenUnsatisfiable: ScheduleAnyway
660,666d652
<       topologySpreadConstraints:
<       - labelSelector:
<           matchLabels:
<             name: querier
<         maxSkew: 1
<         topologyKey: kubernetes.io/hostname
<         whenUnsatisfiable: ScheduleAnyway
739,745d724
<       topologySpreadConstraints:
<       - labelSelector:
<           matchLabels:
<             name: query-frontend
<         maxSkew: 1
<         topologyKey: kubernetes.io/hostname
<         whenUnsatisfiable: ScheduleAnyway
905,911d883
<       topologySpreadConstraints:
<       - labelSelector:
<           matchLabels:
<             name: ruler
<         maxSkew: 1
<         topologyKey: kubernetes.io/hostname
<         whenUnsatisfiable: ScheduleAnyway

Which issue(s) this PR fixes or relates to

N/A

Checklist

• Tests updated.
• Documentation added.
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX].
• about-versioning.md updated with experimental features.

[duricanikolic]

LGTM