tests: find_available_port start search from next port
tests: find_available_port start search from next port

i.e. don't start the search from scratch hitting the used ones again.
this will also reduce the likelihood of collisions (if there are any
left) by increasing the time until we re-use a port we did use in the
past.

pmem/redis,pmem/redis,pmem/redis,pmem/redis