chore: switch from cosmos-sdk/network to testnode package #3319

Job	Run time
lint / golangci-lint	3m 19s
lint / yamllint	9s
markdown-linter / markdown-lint	6s
markdown-linter / markdown-link-check	1m 33s
test / test	8m 20s
test / test-short	52s
test / test-coverage	2m 4s
test / test-fuzz	5m 4s
test / test-race	4m 0s
goreleaser / goreleaser-check	4s
lint / hadolint / hadolint	7s
goreleaser / goreleaser	0s
	25m 38s

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