refactor(db): remove function for periodic backup of RocksDB database

[317787106]

What does this PR do?

Removes the periodic database backup feature (storage.backup) entirely. This includes the backup configuration class, the AspectJ aspect that intercepted pushBlock to trigger copies, the backup utility, and all associated test fixtures and config files.

Closes #6595.

Why are these changes required?

The storage.backup feature was designed to guard against data corruption from disk failures or abrupt process termination (e.g. kill -9). It has since become more harmful than helpful:

1. The original threat no longer applies. Extensive testing has confirmed that kill -9 does not corrupt RocksDB, which was the primary motivation for the feature.
2. Copy times block block synchronisation. As of early 2026, the mainnet state database is close to 3 TB. A single backup copy can take several hours, during which the node cannot sync blocks — a fatal risk to service stability.
3. A better alternative exists. Operators can deploy a primary–backup pair of full nodes using node.backup (UDP keep-alive failover). If one node becomes unavailable, traffic can be switched to the standby without any file-copy disruption.

Changes:

• Deleted DbBackupConfig, BackupDbUtil, BackupRocksDBAspect, NeedBeanCondition (common / framework).
• Removed CommonParameter.dbBackupConfig field and Args.initRocksDbBackupProperty() initialiser.
• Removed ConfigKey.STORAGE_BACKUP_* constants and the conditional backupRocksDBAspect Spring bean from DefaultConfig.
• Deleted BackupDbUtilTest and config-test-dbbackup.conf; updated RocksDbDataSourceImplTest and SupplementTest to use TEST_CONF.
• Configuration change: the storage.backup block is no longer read and has no effect. Nodes carrying this section in their config file can leave it in place without error, but it will be silently ignored.

Backward Compatibility: Not compatible with v4.8.1 or older.

This PR has been tested by:

• Unit Tests

Follow up

Operators who currently rely on storage.backup should migrate to the node.backup primary–backup failover configuration.

Extra details

N/A