[FLINK-37170][ci] Removes 1.18 version from GHA nightly builds #863

Job	Run time
Pre-compile Checks / Basic QA	11m 12s
Default (Java 17) / Compile	39m 58s
Default (Java 17) / Test packaging/licensing	35m 56s
Default (Java 17) / E2E (group 1)	2h 12m 36s
Default (Java 17) / Test (module: core)	19m 18s
Default (Java 17) / E2E (group 2)	2h 11m 39s
Default (Java 17) / Test (module: python)	28m 29s
Default (Java 17) / Test (module: table)	32m 8s
Default (Java 17) / Test (module: connect)	7m 56s
Default (Java 17) / Test (module: tests)	34m 37s
Default (Java 17) / Test (module: misc)	23m 53s
	8h 17m 42s

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