Support Union in Decoupled planning #13113

Job	Run time
Set env var	1s
build (jdk8)	12m 44s
build (jdk11)	12m 21s
build (jdk17)	12m 16s
build (jdk21)	12m 16s
unit tests (jdk8, sql-compat=true) / changes	2s
unit tests (jdk8, sql-compat=false) / changes	2s
unit tests (jdk8, sql-compat=false) / other_modules_test / other modules test	56m 29s
unit tests (jdk8, sql-compat=true) / other_modules_test / other modules test	56m 29s
unit tests (jdk8, sql-compat=true) / processing_modules_test / processing modules test	47m 59s
unit tests (jdk8, sql-compat=true) / server_modules_test / server modules test	7m 55s
unit tests (jdk8, sql-compat=true) / indexing_modules_test / indexing modules test	50m 0s
unit tests (jdk8, sql-compat=false) / indexing_modules_test / indexing modules test	46m 27s
unit tests (jdk8, sql-compat=false) / server_modules_test / server modules test	7m 50s
unit tests (jdk8, sql-compat=false) / processing_modules_test / processing modules test	49m 11s
unit tests (jdk${{ matrix.jdk }}, sql-compat=true)	1s
revised-its	1s
standard-its	1s
	6h 12m 5s

Provide feedback