Figure out why TestStartup seemingly always triggers a 30 second timeout

[KyleMaas]

See #261

Example test run:

2023/01/29 02:41:11 [margaret/indexes/badger] overwrote batch limit 0
=== RUN   TestStartup
2023/01/29 02:41:11 saved identity @7yBz96Bmr/emsDSfugNa+1FQSG4+6SCFJ1Atw/6d3SI=.ed25519 to testrun/TestStartup/secret
    interop_test.go:123: go-sbot: @7yBz96Bmr/emsDSfugNa+1FQSG4+6SCFJ1Atw/6d3SI=.ed25519
level=warn t=52.390822ms unit=gossip event="live qry on rxlog exited"
    interop_test.go:272: timeout
level=debug t=30.054941169s event="network listen loop exited"
level=debug t=30.055147848s event="sbot closing" msg="connections closed"
level=debug t=30.05523864s event="sbot closing" msg="waited for indexes to close"
level=info t=30.117655113s event="sbot closing" msg="closers closed"
    interop_test.go:123: go-sbot: @7yBz96Bmr/emsDSfugNa+1FQSG4+6SCFJ1Atw/6d3SI=.ed25519
--- PASS: TestStartup (30.14s)
level=warn t=30.136709559s unit=gossip event="live qry on rxlog exited"
PASS
ok      github.com/ssbc/go-ssb/tests    30.168s

This test should be able to run considerably faster if we could figure out why it waits for 30 seconds before proceeding. Low priority, but wanted to save this for later so we can investigate.