[MAJOR VERSION] Release 2.0.0

[nschad]

What this PR does:

Changes who require special attention and/or break functionality have been prefixed with BREAKING

Which issue(s) this PR fixes:

• [FEATURE] add purger components to cortex #407
• [BREAKING CHANGE] With the release of memcached v6 bitnami renamed extraEnv to extraEnvVars. Use extraEnvVars if you want to alter MEMCACHED_CACHE_SIZE, MEMCACHED_MAX_CONNECTIONS, etc... #303
• [BREAKING CHANGE] Caching for block storage can now be individually enabled. For example use memcached-blocks.enabled to enable caching for blocks. #417
• [BREAKING CHANGE] Drop cortex chunk support. #417
• [BREAKING CHANGE] Drop cortex configdb support. #417
• [BREAKING CHANGE] Removed legacy ruler and alertmanager storage configuration. Please use ruler_storage and alertmanager_storage. #417
• [BREAKING CHANGE] Dropped storage.index_queries_cache_config. #417
• [ENHANCEMENT] Add verboseLogging option to nginx config #402
• [ENHANCEMENT] Start using autoscaling/v2 for HorizontalPodAutoscaler in v1.23+ #414
• [ENHANCEMENT] Add pod topology spread constrant option to Ingester/Alertmanager statefulset #403
• [ENHANCEMENT] Add HPA to store gateways #406
• [DEPENDENCY] Update quay.io/cortexproject/cortex Docker tag to v1.13.1 #401
• [DEPENDENCY] Update Helm release memcached to v6 #303
• [DEPENDENCY] Update Helm release memcached to v6.3.2 #418
• [DEPENDENCY] Update Cortex to v1.14 #417

Checklist

• [x] CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]