Fix flake8 errors/warnings about import in cubicweb/_exceptions.py We either ignore errors in case of name re-exports and drop re-exports from old backwards compatibility. We fix the only occurrence of NoSelectableObject being imported from cubicweb in tests and update the import to use lgc instead.

Release notes
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.. toctree::
    :maxdepth: 1

    3.25
    3.24
    3.23
    3.22
    3.21
    3.20
    3.19
    3.18
    3.17
    3.16
    3.15
    3.14