in-process invocation of a test runner fails with "Recording already in progress"

If one of the supported test runners (e.g. pytest, unittest) is run in-process, the enabled recording methods for the process apply to the test runner.

For example, in this test, the sqlmesh plan subcommand uses a click.testing.CliRunner to run a unittest test, which fails:

tests/cli/test_cli.py::test_plan 
----------------------------------------------------------------------
Test Failure Summary
======================================================================
Num Successful Tests: 0
Failure Test: sqlmesh_example.full_model test_example_full_model
======================================================================
E
======================================================================
ERROR: test_example_full_model (/private/var/folders/2g/xqtf8_tn5j1861bbkvvhtmmr0000gn/T/pytest-of-ajp/pytest-159/test_plan0/tests/test_full_model.yaml)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/ajp/src/applandinc/appmap-python/_appmap/wrapt/wrappers.py", line 744, in __call__
    return self._self_wrapper(self.__wrapped__, self._self_instance,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ajp/src/applandinc/appmap-python/_appmap/unittest.py", line 36, in callTestMethod
    with _session.record(test_case.__class__, method_name, location=location) as metadata:
  File "/Users/ajp/.asdf/installs/python/3.12.2/lib/python3.12/contextlib.py", line 137, in __enter__
    return next(self.gen)
           ^^^^^^^^^^^^^^
  File "/Users/ajp/src/applandinc/appmap-python/_appmap/testing_framework.py", line 119, in record
    with rec, environ.disabled("requests"):
  File "/Users/ajp/src/applandinc/appmap-python/_appmap/recording.py", line 47, in __enter__
    self.start()
  File "/Users/ajp/src/applandinc/appmap-python/_appmap/recording.py", line 32, in start
    r.start_recording()
  File "/Users/ajp/src/applandinc/appmap-python/_appmap/recorder.py", line 108, in start_recording
    cls.get_current()._start_recording()  # pylint: disable=protected-access
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ajp/src/applandinc/appmap-python/_appmap/recorder.py", line 236, in _start_recording
    super()._start_recording()
  File "/Users/ajp/src/applandinc/appmap-python/_appmap/recorder.py", line 158, in _start_recording
    raise RuntimeError("Recording already in progress")
RuntimeError: Recording already in progress

----------------------------------------------------------------------
Ran 1 test in 0.165s

FAILED (errors=1)

Error: Cannot generate plan due to failing test(s). Fix test(s) and run again

FAILED

============================================================================================ FAILURES ============================================================================================

Reproduce the failure from tests/cli/test_cli.py::test_plan, then trace the nested recording flow through _appmap/unittest.py, testing_framework.py, recording.py, and recorder.py. Verify that an in-process test runner no longer raises "Recording already in progress" and that the plan test completes successfully.