change(scan): Remove support for starting the scanner at `zebrad` startup #1401

Job	Run time
Check deny.toml bans	28s
Check deny.toml bans --features default-release-binaries	27s
Check deny.toml bans --all-features	33s
Check deny.toml sources	29s
Check deny.toml sources --features default-release-binaries	30s
Check deny.toml sources --all-features	30s
Check Cargo.lock is up to date	1m 6s
Install zebrad from lockfile without cache on ubuntu-latest	1m 18s
Test stable on ubuntu-latest	1m 18s
Test beta on ubuntu-latest	1m 17s
Test stable on macos-latest	1m 17s
Check for unused dependencies	21s
Test stable on windows-latest	47s
Test beta on windows-latest	1m 0s
Open or update issues for OS integration failures	1s
	11m 22s

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