fix(server): handle incomplete RocksDB with missing column families gracefully

[cauchy1988]

Problem

When a replica server crashes during DB::Open (e.g. OOM, kill -9), it may leave an incomplete rdb directory — the MANIFEST contains only partial column families (e.g. only pegasus_data without pegasus_meta). On restart, the server hits:

CHECK_PREFIX_MSG(!missing_meta_cf, "You must upgrade Pegasus server from 2.0");

and aborts immediately, making the replica unrecoverable.

Root Cause

• The crash leaves a partially created RocksDB directory (rdb_path exists but is incomplete)
• On restart, db_exist = true and the code enters the "open existing DB" path
• check_column_families() detects missing_meta_cf = true or missing_data_cf = true
• The CHECK_PREFIX_MSG causes a hard abort

An incomplete DB is unusable anyway (cannot read decree, data version, etc. from it), so crashing is unnecessary.

Fix

When missing_meta_cf || missing_data_cf is detected:

1. Log a WARNING with details about the incomplete state
2. Remove the corrupted rdb directory
3. Set db_exist = false
4. Fall through to create a fresh DB — the replica will re-sync data from the primary

The existing db_exist branch (LoadLatestOptions etc.) is wrapped in if (db_exist) to avoid operating on the deleted directory.

Testing

• Verified that the fix resolves the crash in Docker development environment (Docker for Mac ARM64)
• The replica successfully creates a new DB and re-syncs from primary after the corrupted directory is removed
• Ran ./run.sh test -m base_api_test: integration_test.write_corrupt_db and integration_test.read_corrupt_db now pass. This also resolves base_api_test failed due to the failure of a replica server #2283, where the replica dropped on a corrupted DB (get_alive_replica_server_count() returned 2) and cascaded into 49 failures across the whole suite.

Related

Closes #2215
Closes #2283