fix: base node database error code (#6770)

Description
---
Fixes database error code returned on base node start if database is
corrupted.

applications/minotari_node/src/lib.rs

@@ -147,7 +147,7 @@ pub async fn run_base_node_with_cli(
     }
 
     ctx.start()
-        .map_err(|e| ExitError::new(ExitCode::UnknownError, &format!("Could not start database.{:?}", e)))?;
+        .map_err(|e| ExitError::new(ExitCode::DatabaseError, &format!("Could not start database.{:?}", e)))?;
 
     // Run, node, run!
     let context = CommandContext::new(&ctx, shutdown.clone());