obsdiscovery: adopt to calling convention change Upstream commits 71d83b315778 and abce899c985f changed the calling convention of setdiscovery._takefullsample(). We inspect the signature of the function before calling it so we can pass the proper arguments.

test-drop.t
test-inhibit.t
test-simple4server.t
tests/test-simple4server-bundle2.t