Convert FLOAT64 to NUMERIC in UNION ALL #19610
Description
Analyzer does not reject UNION ALL DOUBLE, for example 2.3 UNION ALL 2.1. BeamSQL does not execute when DOUBLE is in GBK (as UNION ALL is implemented based on GBK).
Investigate why DOUBLE appears in GBK in UNION ALL implementation, try to fix it, and if it's not feasible, at least need throw exception in planner.
Imported from Jira BEAM-8051. Original Jira may contain additional context.
Reported by: amaliujia.