fix(blooms): Delete outdated metas during planning

[salvacorts]

What this PR does / why we need it:
If a planner crashes before receiving all tasks for a given tenant-table combination, it will not delete the outdated metas and blocks. This PR fixes this by also deleting outdated metas during the planning phase. Thereafter, gaps will be computed only with the metas that are up to date.

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
• For Helm chart changes bump the Helm chart version in production/helm/loki/Chart.yaml and update production/helm/loki/CHANGELOG.md and production/helm/loki/README.md. Example PR
• 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

[chaudum]

nit: The function name is slightly misleading. Maybe add a comment what the function does and what it returns.