Log query and response when using isctest.query.*

Log query and response when using isctest.query.*

Make sure the queries and responses are logged at the DEBUG level, which
may provide useful information in case of failing tests.

This doesn't seem to significantly increase the overall artifacts size.
Previously, pytest.log.txt files from all system tests would take around
3 MB, with this change, it's around 8 MB).

(cherry picked from commit 56fec9ba04b3ddb82591d2c9edf4f073d650209c)