test_common: create_*: detect changes all parameters

test_common: create_*: detect changes all parameters

Data::Dumper+B::Deparse seems fast enough to generate cache keys
with, so this makes updating and developing tests easier (as
opposed to forcing the developer to change the identifier).  The
main downside is we'll have to deal with cache expiration, but
"make clean" seems overly aggressive already (it keeps blowing
away the clones made by t/cindex-join.t :<)