Disable spill for probe only grouped execution

[rschlussel]

This PR is to unblock safely rolling out spill for join. Spill for joins where only the probe side uses grouped execution was broken because some code relied on having a fixed number of probe operators for each build operator. These queries would fail with errors like "5 probe operators finished out of 4 declared"

A proper fix would be to remove the dependency on a fixed number of probe operators, and instead do something similar to how JoinLifecycle works, where you keep track of how many probe operator references you have, and only destroy the build table if all probe operators have finished and the LookupJoinOperatorFactory is closed. But that fix requires more rigorous testing to ensure we're able to keep unspilling and respilling the partitions of the hash table.

Test plan - Verifier. I had trouble writing a test that would reliably finish, but I ran this with verifier on queries I had previously seen failures on, and the errors went away.

== RELEASE NOTES ==

General Changes
* Disable spill to disk for join queries where the probe side uses grouped execution and the build does not.  Previously these queries would fail with generic_internal_errors.