fix: Make AbstractOperatorExtension use the kubernetesClient if the infrastructureKubernetesClient is not set #5855

Job	Run time
check_format_and_unit_tests	1m 25s
build / Special integration tests (25)	2m 29s
build / Special integration tests (21)	2m 49s
build / Special integration tests (17)	2m 32s
build / integration_tests (17, 1.32.4) / Integration tests (17, 1.32.4, vertx)	25m 37s
build / integration_tests (17, 1.30.12) / Integration tests (17, 1.30.12, vertx)	24m 22s
build / integration_tests (17, 1.33.1) / Integration tests (17, 1.33.1, vertx)	26m 17s
build / integration_tests (21, 1.31.8) / Integration tests (21, 1.31.8, vertx)	26m 0s
build / integration_tests (21, 1.32.4) / Integration tests (21, 1.32.4, vertx)	24m 57s
build / integration_tests (21, 1.33.1) / Integration tests (21, 1.33.1, vertx)	25m 38s
build / integration_tests (25, 1.31.8) / Integration tests (25, 1.31.8, vertx)	26m 11s
build / integration_tests (25, 1.30.12) / Integration tests (25, 1.30.12, vertx)	24m 2s
build / integration_tests (17, 1.31.8) / Integration tests (17, 1.31.8, vertx)	26m 12s
build / integration_tests (25, 1.32.4) / Integration tests (25, 1.32.4, vertx)	24m 39s
build / integration_tests (21, 1.30.12) / Integration tests (21, 1.30.12, vertx)	24m 34s
build / httpclient-tests (vertx) / Integration tests (25, 1.32.0, vertx)	25m 28s
build / httpclient-tests (jetty) / Integration tests (25, 1.32.0, jetty)	25m 25s
build / httpclient-tests (jdk) / Integration tests (25, 1.32.0, jdk)	25m 8s
build / integration_tests (25, 1.33.1) / Integration tests (25, 1.33.1, vertx)	25m 14s
	6h 28m 59s

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