Refactors the App Engine Jetty runtime by extracting several nested c… #1865

Job	Run time
build (ubuntu-latest, 21, temurin)	21m 49s
build (ubuntu-latest, 17, temurin)	23m 29s
build (ubuntu-latest, 25, temurin)	17m 40s
build (ubuntu-latest, 27-ea, temurin)	18m 14s
	1h 21m 12s

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