itest: Extend custom channel liquidity itest for RFQ HTLC tracking #1888

Job	Run time
frontend tests on ubuntu-latest	2m 10s
integration test	19m 24s
frontend tests on windows-latest	9m 30s
check commits	4m 22s
frontend tests on macOS-latest	2m 6s
backend build on ubuntu-latest	7m 39s
lint	5m 26s
RPC proto compilation check	5m 47s
backend build on windows-latest	17m 5s
check release notes updated	3s
backend build on macOS-latest	6m 2s
unit tests	4m 18s
unit-race	5m 17s
	1h 29m 9s

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