Add backup_writer_failure_HABITAT test and golden patch

[Ngarari4910]

Task

Update the BadgerDB backup mechanism to correctly handle writer failures during DB.Backup.
Currently, if the writer fails during backup, the error is not propagated properly.

This task requires:

• Introducing a test TestBackupWriterFailure_HABITAT that simulates a writer error.
• Ensuring DB.Backup returns an error if the writer fails.
• Writing a golden patch to fix the backup logic and pass the test.

The test must use the __HABITAT suffix to ensure Habitat validation works.

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