tests: disable summary of xpassed/xfailed tests

With pytest-dev/pytest#11233, enabling summaries for xfailed tests
also enables their full error tracebacks, which complicates finding
the actual test failures. There is no way of disabling just the
tracebacks, so disable the summaries of xpassed/xfailed tests
altogether.

setup.cfg

@@ -49,9 +49,11 @@ extend-ignore = E265
 max-line-length=120
 
 [tool:pytest]
-# Display summary info for (s)skipped, (x)xfailed, (X)xpassed, (f)failed and (E)errored tests
+# Display summary info for (s)skipped, (f)failed and (E)errored tests.
+# Do not enable summary for (x)xfailed and (X)xpassed tests, because as
+# of pytest-dev/pytest#11233, this includes full tracebacks.
 # Skip doctest text files
-addopts=--maxfail=3 -m "not slow" -v -rsxXfE --doctest-glob=
+addopts=--maxfail=3 -m "not slow" -v -rsfE --doctest-glob=
 
 markers =
     darwin: only run on macOS