Fix: Autoshielding OBO error.

The ANCHOR_OFFSET is already accounted for in the underlying rust code so this simple change prevents adding additional confirmation blocks. In the next iteration we may want to adjust the logic in librustzcash to not accept a confirmation parameter for the shielding function or at least improve the way it works:
https://github.com/nuttycom/librustzcash/blob/autoshield-poc-daa/zcash_client_backend/src/data_api/wallet.rs#L353

src/main/rust/lib.rs

@@ -1145,7 +1145,7 @@ pub unsafe extern "C" fn Java_cash_z_ecc_android_sdk_jni_RustBackend_shieldToAdd
             &sk,
             &extsk,
             &MemoBytes::from(&memo),
-            10
+            0
         )
             .map_err(|e| format_err!("Error while shielding transaction: {}", e))
     });