Avoid forced function call delegation after metadata change + parallel operation

When we force function call delegation within a transaction, the transaction could previously have modified the metadata (e.g. created a distributed table) over one connection and modified shards (e.g. created shards) over another. In that case, there is no appropriate connection to perform the function on, but we still try to push it down over the one that modified the shard. We should avoid pushdown in such cases.