rename test hooks python file

As bin/tests/system/hooks/tests_hooks.py still contains wrapper to a
shell-based test (even if not only), rename the file name into
tests_sh_hooks.py

diff --git a/bin/tests/system/hooks/tests_hooks.py b/bin/tests/system/hooks/tests_sh_hooks.py
similarity index 100%
rename from bin/tests/system/hooks/tests_hooks.py
rename to bin/tests/system/hooks/tests_sh_hooks.py