Change the relocatable related command line to compare to cached versions

[fruch]

Right now doing

ccm create scylla-reloc-1 -n 1 --scylla --version unstable/master:390

and then

ccm create scylla-reloc-1 -n 1 --scylla --version unstable/master:390 --scylla-core-package-uri=../scylla-next/build/release/scylla-package.tar.gz

Second command won't have effect (i.e. scylla-package.tar.gz won't be used) since version are cached only base on the --version argument