precursor to Split out test_pytables.py to sub-module of tests
- precursor to #18498
- All tests in test_pytables are passing
@simonjayhawkins as discussed this is the pre work to splitting this large test file into smaller files. So far, I have fixturised the class base class and updated methods using self.path from base to use the setup_path fixture instead.

Next I plan to create a test file for TestTimezones class and make the test functional so the class itself is no longer required.
Once this is running fine, I will then apply similar approach to the other bigger classes.