[multistage] Add tests for chaining colocated operations without data shuffle

[yashmayya]

Follow-up to #18804 (now merged). Adds test coverage verifying that colocated operations can be chained without a data shuffle: when a chain of joins / window functions / set operations is all keyed on the same partition column and the colocation hints are applied, every inter-stage hash exchange in the plan is pre-partitioned (direct, 1-to-1) and no full shuffle is inserted anywhere in the chain.

This exercises the interaction of the three colocation hints:

• joinOptions(is_colocated_by_join_keys='true')
• windowOptions(is_partitioned_by_window_keys='true')
• setOpOptions(is_colocated_by_set_op_keys='true')

Tests added (test-only, no production changes):

• QueryCompilationTest: a planner-level invariant check (testColocatedOperationsChainWithoutShuffle) that asserts every hash-distributed exchange in the plan is pre-partitioned, across four chains:

  • colocated join → window
  • set op of two colocated joins
  • set op of two colocated windows
  • the triple: colocated join → window → set op

  Plus two baselines proving the hints are load-bearing (so the positive assertions are not vacuous): testChainWithoutColocationHintsStillShuffles (the same join → window chain shuffles without the hints) and testSetOpChainWithoutSetOpHintShuffles (with is_colocated_by_set_op_keys='false' the set-op level of the chain shuffles again).

• QueryHints.json: two H2-validated runtime cases (a colocated join → window, and a UNION ALL of two colocated joins) on tables physically partitioned by the key, confirming the chained colocation also produces correct results on both the V1 and V2 engines.

Hint placement note: because a set operation is an ancestor of its branch SELECTs, chaining through a set op uses the outer-SELECT-wrap form for the set-op hint with the join/window hints on each branch — this is what lets colocation propagate through every level of the chain.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.25%. Comparing base (f054a90) to head (71dc519).

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #18997      +/-   ##
============================================
+ Coverage     65.23%   65.25%   +0.01%     
  Complexity     1405     1405              
============================================
  Files          3419     3419              
  Lines        214702   214702              
  Branches      33931    33931              
============================================
+ Hits         140067   140094      +27     
+ Misses        63349    63324      -25     
+ Partials      11286    11284       -2     

Flag	Coverage Δ
custom-integration1	100.00% <ø> (ø)
integration	100.00% <ø> (ø)
integration1	100.00% <ø> (ø)
integration2	0.00% <ø> (ø)
java-21	65.25% <ø> (+0.01%)	⬆️
temurin	65.25% <ø> (+0.01%)	⬆️
unittests	65.24% <ø> (+0.01%)	⬆️
unittests1	56.89% <ø> (+0.02%)	⬆️
unittests2	37.74% <ø> (-0.01%)	⬇️

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[gortiz]

LGTM