tests: blacklist test-demandimport from test-check-module-imports

It just does too much weird import stuff to have a hope of passing the
checks.

tests/test-check-module-imports.t

@@ -1,42 +1,43 b''
 #require test-repo
 
   $ . "$TESTDIR/helpers-testrepo.sh"
   $ import_checker="$TESTDIR"/../contrib/import-checker.py
 
   $ cd "$TESTDIR"/..
 
 There are a handful of cases here that require renaming a module so it
 doesn't overlap with a stdlib module name. There are also some cycles
 here that we should still endeavor to fix, and some cycles will be
 hidden by deduplication algorithm in the cycle detector, so fixing
 these may expose other cycles.
 
 Known-bad files are excluded by -X as some of them would produce unstable
 outputs, which should be fixed later.
 
   $ testrepohg locate 'set:**.py or grep(r"^#!.*?python")' \
   > 'tests/**.t' \
   > -X hgweb.cgi \
   > -X setup.py \
   > -X contrib/debugshell.py \
   > -X contrib/hgweb.fcgi \
   > -X contrib/python-zstandard/ \
   > -X contrib/win32/hgwebdir_wsgi.py \
   > -X doc/gendoc.py \
   > -X doc/hgmanpage.py \
   > -X i18n/posplit \
   > -X tests/hypothesishelpers.py \
   > -X tests/test-commit-interactive.t \
   > -X tests/test-contrib-check-code.t \
+  > -X tests/test-demandimport.py \
   > -X tests/test-extension.t \
   > -X tests/test-hghave.t \
   > -X tests/test-hgweb-auth.py \
   > -X tests/test-hgweb-no-path-info.t \
   > -X tests/test-hgweb-no-request-uri.t \
   > -X tests/test-hgweb-non-interactive.t \
   > -X tests/test-hook.t \
   > -X tests/test-import.t \
   > -X tests/test-imports-checker.t \
   > -X tests/test-lock.py \
   > -X tests/test-verify-repo-operations.py \
   > | sed 's-\\-/-g' | $PYTHON "$import_checker" -