Use os.path.realpath() instead of abspath()

$ git bisect start master release-4.4.5
$ git bisect run python -m pytest -n1 tests/old_functional/test_direct_edit.py::TestDirectEdit::test_attachments
# (...)
fbe5393c3f070e89f52c616dc1f8466aa3618665 is the first bad commit
commit fbe5393c3f070e89f52c616dc1f8466aa3618665
Author: Mickaël Schoentgen <mschoentgen@nuxeo.com>
Date:   Mon Oct 19 15:18:28 2020 +0200

    NXDRIVE-2319: Do not use the undocumented and unreliable Path.absolute() method

 docs/changes/4.4.6.md           |  2 ++
 nxdrive/client/local/base.py    | 19 ++++---------------
 nxdrive/utils.py                | 13 ++++---------
 tests/unit/test_local_client.py | 18 ------------------
 tests/unit/test_utils.py        | 15 ---------------
 5 files changed, 10 insertions(+), 57 deletions(-)
bisect run success