Put True/False lowercase linting under check_codestyle

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = packaging, py35, py36, py37, check_codestyle, check_isort, check_config
+envlist = packaging, py35, py36, py37, check_codestyle, check_isort
 
 [base]
 basepython = python3.7
@@ -118,15 +118,13 @@ deps =
 commands =
     python -m black --check --diff .
     /bin/sh -c "flake8 synapse tests scripts scripts-dev scripts/hash_password scripts/register_new_matrix_user scripts/synapse_port_db synctl {env:PEP8SUFFIX:}"
+    {toxinidir}/scripts-dev/lint-config.sh
 
 [testenv:check_isort]
 skip_install = True
 deps = isort
 commands = /bin/sh -c "isort -c -df -sp setup.cfg -rc synapse tests"
 
-[testenv:check_config]
-commands = {toxinidir}/scripts-dev/lint-config.sh
-
 [testenv:check-newsfragment]
 skip_install = True
 deps = towncrier>=18.6.0rc1