fix(hermetic-build): use correct image name in templated graalvm jobs #10764

Job	Run time
build(21) except self-service clients	13m 30s
build (17)	13m 59s
build (11)	14m 19s
build(8) except for gapic-generator-java	4m 10s
unmanaged_dependency_check	5m 26s
dependency_analyzer_unit_test	16s
compatibility	1m 19s
gapic-generator-java-bom	1m 46s
lint	46s
showcase-clirr	3m 22s
build(8) for gapic-generator-java	11m 43s
showcase (17)	9m 16s
showcase (11)	9m 1s
showcase (21)	8m 57s
showcase (23)	9m 33s
	1h 47m 23s

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