test(tesseract): record postgres result snapshot for FK-aggregate fix

Adds the canonical row-data snapshot the regression test needs when
`integration-postgres` is enabled. Validates that the filtered count
on a primary key produces the correct distinct-customer counts (1 for
'completed', 1 for 'pending', 0 for orders.status NULL) — pre-fix the
buggy cross-join over-counted these.

Author: tlangton3

rust/cubesqlplanner/cubesqlplanner/src/tests/integration/snapshots/cubesqlplanner__tests__integration__multi_fact__multiplied_aggregate_filtered_count_on_pk.snap

@@ -0,0 +1,9 @@
+---
+source: cubesqlplanner/src/tests/integration/multi_fact.rs
+expression: result
+---
+orders__status | customers__active_count
+---------------+------------------------
+completed      | 1                      
+pending        | 1                      
+NULL           | 0