tempo-distributed: add podDisruptionBudget.enabled flag to allow disabling PDBs

[armanfeyzi]

What this PR does

This adds a podDisruptionBudget.enabled flag to all components in the tempo-distributed chart so users can disable PodDisruptionBudgets when needed.

Why

Previously there was no way to opt out of PDBs - they were always created when replicas > 1. Some users need to disable PDBs in certain environments (like dev/test clusters) or have their own PDB management.

This is consistent with how many other Helm charts handle PDBs.

Changes

• Add podDisruptionBudget.enabled check to all 9 PDB templates
• Add podDisruptionBudget section to values.yaml for each component
• Set enabled: true by default to keep current behavior (no breaking change)
• Bump chart version to 1.59.0
• Regenerate README.md

Components affected

• compactor
• distributor
• ingester
• querier
• query-frontend
• metrics-generator
• gateway
• memcached
• enterprise-federation-frontend

Example usage

To disable PDB for a specific component:

ingester:
  podDisruptionBudget:
    enabled: false

[CLAassistant]

All committers have signed the CLA.

[QuentinBisson]

LGTM, let's wait for the CI. Thank you for the contribution