Refactor integration test harness #1031

Job	Run time
unit-tests	1m 11s
build-test-bins	1m 20s
integration-tests (bitcoin_mixed)	4m 27s
integration-tests (liquid_mixed)	4m 27s
integration-tests (bitcoin_lndlnd)	3m 12s
integration-tests (lnd)	3m 21s
integration-tests (bitcoin_clncln)	3m 33s
integration-tests (liquid_lndlnd)	3m 0s
integration-tests (liquid_clncln)	3m 29s
integration-tests (misc_1)	4m 39s
integration-tests (misc_3)	4m 39s
integration-tests (misc_2)	3m 42s
unit-tests	1m 11s
integration-tests (bitcoin_mixed)	4m 27s
integration-tests (liquid_clncln)	3m 29s
build-test-bins	1m 20s
integration-tests (bitcoin_lndlnd)	3m 12s
integration-tests (lnd)	3m 21s
integration-tests (bitcoin_clncln)	3m 33s
integration-tests (liquid_lndlnd)	3m 0s
integration-tests (misc_2)	3m 42s
integration-tests (misc_1)	4m 39s
integration-tests (liquid_mixed)	4m 27s
integration-tests (misc_3)	4m 37s
	1h 21m 58s

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