fix(coverage): pass script path directly to slipcover instead of via python subprocess

The coverage_report nox session was passing 'python scripts/run_behave_parallel.py'
as the command to slipcover's '--' separator. This caused slipcover to spawn an
uninstrumented Python subprocess, preventing coverage data from being collected.

Fix: pass the script path directly (without 'python' prefix) so slipcover runs
the script in-process and can instrument it correctly. This matches the behavior
of the old console-script entry point approach.

Closes #8168

noxfile.py

@@ -508,10 +508,13 @@ def coverage_report(session: nox.Session):
         path.unlink()
 
     # Build behave runner args (sequential for coverage).
+    # Pass the script path directly (not via "python script.py") so that
+    # slipcover can instrument the script in-process rather than spawning
+    # an uninstrumented Python subprocess.  Slipcover's "--" separator
+    # accepts a Python script path and runs it in the same interpreter.
     behave_runner = str(BEHAVE_PARALLEL_SCRIPT)
     if session.posargs and session.posargs[0].endswith(".feature"):
         behave_args = [
-            "python",
             behave_runner,
             "-q",
             "--no-capture",
@@ -519,7 +522,6 @@ def coverage_report(session: nox.Session):
         ]
     else:
         behave_args = [
-            "python",
             behave_runner,
             "-q",
             "--no-capture",