Fix context mocking for CondaSession test

[kenodegard]

Description

Discovered in #13062 (comment):

With the addition of new tests above the testing order was shuffled and exposed incorrect context mocking in this unrelated test, see https://github.com/conda/conda/actions/runs/6079217031/job/16498615642#step:8:909

...

The failure can be replicated on main with the following test order:

pytest \
    "tests/gateways/test_connection.py::test_get_session_with_channel_settings_no_handler" \
    "tests/gateways/test_jlap.py::test_jlap_fetch" \
    "tests/gateways/test_jlap.py::test_jlap_fetch_file" \
    "tests/gateways/test_jlap.py::test_download_and_hash" \
    "tests/gateways/test_jlap.py::test_jlap_cache_clock[True]"

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[dholth]

Not a big fan of mock objects but LGTM