PYMCA_DATA_DIR patching in setup.py: do not use defaultDataPath

[woutdenolf]

The idea sounds good to me. However, I imagine it might prevent testing the code from the source directory prior to installation unless the search is modified.

If we don't install the project then setup.py does not patch PyMcaDataDir.py and we still have PYMCA_DATA_DIR = r'DATA_DIR_FROM_SETUP' which triggers the search.

I still think patching PyMcaDataDir.py with the defaultDataPath in setup.py can be removed. Hard-coding a relative path when installing/building a project is not a good idea imo.

Originally posted by @woutdenolf in #1198 (comment)

[sergey-yaroslavtsev]

From my perspective i totally agreed.

This hardcoded relative path adds unwanted behavior that in the CI the data for tests are read from repo instead of from inner files of installed PyMca.

Of course it is not a big issue but it creates uncertainty if we will be able to run tests in frozen binaries.
Assume someone will modify PyMcaDataDir that searching for proper folder will be ruined or if data will be moved to another folder, etc... then tests in CI could work but can fail in actually installed version.

Removing relative path will trigger the search which should find the proper data folder. In any "weird" scenario anyway this path with ./src should not exist and trigger the search (or if os.env is set it will be used).

I could not imagine scenario when ./src exist and correct + it is used but search will fail.