op_transaction end_read_tx in case of begin_write_tx is busy

In case of starting a write txn, we always start by starting a read txn.
If we don't end_read_tx then it will never release locks.

core/vdbe/execute.rs

@@ -1709,6 +1709,7 @@ pub fn op_transaction(
 
         if updated && matches!(new_transaction_state, TransactionState::Write) {
             if let LimboResult::Busy = pager.begin_write_tx()? {
+                pager.end_read_tx()?;
                 tracing::trace!("begin_write_tx busy");
                 return Ok(InsnFunctionStepResult::Busy);
             }