Previously there are a lot of warning messages of setuptools
in the log files of tox jobs. This is mainly caused by test
samples because these are in python codes directories.
This patch moves test samples from under {tacker_root}/tacker/
to under {tacker_root}/samples/.
This patch reduces log messages drastically. For example,
the log file of py38 tox job decreased about 34,000 lines.
Change-Id: I8187ef892c6fe8be323fa5cc20969d298843f1ea
c056e248b2