Finalize 637 support for istio egress gateway #2570

Job	Run time
calico-tests-orig-vs-opt-comparison	51s
fw-rules-assertion-tests	43s
build_package	23s
calico-tests	1m 53s
istio-tests	1m 8s
istio-tests-orig-vs-opt-comparison	1m 12s
k8s-tests	1m 34s
k8s-tests-orig-vs-opt-comparison	1m 57s
lint	12s
test-docker	35s
test-docker-ubi	51s
unit-tests	11s
test_package	14s
	11m 44s

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