ingest/ledgerbackend: Update captive-core config with new BucketlistDB parameters

[urvisavla]

PR Checklist

PR Structure

• This PR has reasonably narrow scope (if not, break it down into smaller PRs).
• This PR avoids mixing refactoring changes with feature changes (split into two PRs
  otherwise).
• This PR's title starts with name of package that is most changed in the PR, ex.
  services/friendbot, or all or doc if the changes are broad or impact many
  packages.

Thoroughness

• This PR adds tests for the most critical parts of the new functionality or fixes.
• I've updated any docs (developer docs, .md
  files, etc... affected by this change). Take a look in the docs folder for a given service,
  like this one.

Release planning

• I've updated the relevant CHANGELOG (here for Horizon) if
  needed with deprecations, added features, breaking changes, and DB schema changes.
• I've decided if this PR requires a new major/minor version according to
  semver, or if it's mainly a patch change. The PR is targeted at the next
  release branch if it's not a patch change.

What

• Adds the new stellar-core BucketListDB related config parameter DEPRECATED_SQL_LEDGER_STATE. It also addresses the EXPERIMENTAL_BUCKETLIST_DB parameter, which will be completely removed in the next Stellar-core release, making DEPRECATED_SQL_LEDGER_STATE mandatory.

• Horizon currently has a an option called CAPTIVE_CORE_USE_DB (to be deprecated) to use captive-core in in-memory mode. The default value of DEPRECATED_SQL_LEDGER_STATE is determined based on this flag: true for in-memory mode and false for the on-disk (preferred) mode. This check will not be necessary once the CAPTIVE_CORE_USE_DB flag is fully removed.

• It also updates the parameter names: EXPERIMENTAL_BUCKETLIST_DB_INDEX_PAGE_SIZE_EXPONENT to BUCKETLIST_DB_INDEX_PAGE_SIZE_EXPONENT and EXPERIMENTAL_BUCKETLIST_DB_INDEX_CUTOFF to BUCKETLIST_DB_INDEX_CUTOFF

This should not be merged until protocol 21 has been voted on and everyone has had the chance to update to stellar-core 21.

Why

Addresses #5295

Known limitations

This PR completely removes the EXPERIMENTAL_BUCKETLIST_DB flag, which we currently use in our deployment. This means we will need to update our deployment scripts as part of the releasing this change.

[sreuland]

nice work, left minor comments for consideration.

[sreuland]

since EXPERIMENTAL_BUCKETLIST_DB is now removed, it effectively means any horizon ingestion node will only work when captive core bin on host is min v21 or higher. So, should this include a sanity check do be run as part of captive core init of horizon ingestion startup, to fail fast with error on command line, if captive core bin version is less than v21? via toml.go coreVersion.IsEqualOrAbove