[CALCITE-6665] Add isEmpty metadata to check if a relational expressi… #14371

Job	Run time
Windows (JDK 17)	14m 36s
Linux (JDK 8, oldest Guava, America/New_York Timezone)	11m 3s
Windows (JDK 8)	16m 34s
Windows (JDK 21)	15m 57s
Linux (JDK 11, Pacific/Chatham Timezone)	10m 56s
Linux (JDK 8, latest Guava, America/New_York Timezone)	12m 17s
Linux (JDK 21)	10m 22s
Linux (JDK 17)	10m 18s
Linux (JDK 11, Avatica main)	14m 20s
Linux (JDK 23)	12m 23s
ErrorProne (JDK 11, latest Guava)	4m 11s
macOS (JDK 21)	45m 42s
CheckerFramework (JDK 11)	10m 52s
CheckerFramework (JDK 11, oldest Guava)	10m 54s
Druid Tests	7m 5s
Linux (JDK 8) Slow Tests	4m 19s
	3h 31m 49s

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