The catchup loop in the outbound eviction functional test currently has
a small flaw, as the contained waiting for a `getheaders` message just
waits for any such message instead of one with the intended block hash.
The reason is that the `prev_prev_hash` variable is set incorrectly,
since the `tip_header` instance is not updated and its field `.hash` is
None. Fix that by updating `tip_header` and use the correct field -- we
want the tip header's previous hash (`.hashPrevBlock`).
Peer protection is only given to outbound-full-relay peers. Add a negative
test to check that other type of outbound peers are not given protection under
the circumstances that outbound-full-relay would