registration: increase timeout waiting for OpenSIPS #380

Job	Run time
setup-matrix	4s
test (accounting, ubuntu-latest)	1m 35s
test (auth, ubuntu-latest)	2m 10s
test (b2b, ubuntu-latest)	6m 33s
test (dialog, ubuntu-latest)	2m 47s
test (permissions, ubuntu-latest)	59s
test (presence, ubuntu-latest)	53s
test (record-route, ubuntu-latest)	56s
test (registration, ubuntu-latest)	4m 23s
test (startup, ubuntu-latest)	1m 14s
test (stir-shaken, ubuntu-latest)	4m 58s
test (topology-hiding, ubuntu-latest)	2m 44s
test (uac-auth, ubuntu-latest)	2m 52s
	32m 8s

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