chore(ksonnet)!: clean-up deprecated configs

[ashwanthgoli]

What this PR does / why we need it:

• Remove deprecated storage backend configs (cassandra, dynamo, bigtable)
• Removes table manager config and workload
• storage_backend config is now simplified to accept a single backend type
• Use tsdb and schema v13 by default

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[periklis]

LGTM. Quick question what is the case for Azure in storage_backend?

[ashwanthgoli]

@periklis added one for azure