fix(README): Update instructions to only use kustomize (#1455) #1677

Job	Run time
check-license	4s
backend-integration	8s
check-doc-links	10s
check-mdtoc	3s
python-lint	23s
progress-report	1m 23s
python-unittest (3.8)	1m 12s
run-pipelineloop-unittests	2m 58s
python-unittest (3.9)	1m 14s
run-go-unittests	3m 52s
run-v2-custom-controller-image-builds	6s
python-unittest (3.10)	1m 11s
validate-testdata	2m 55s
python-unittest (3.11)	1m 5s
	16m 44s

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