Switch to the new, more understandable bcond syntax

Now when https://pagure.io/fedora-ci/general/issue/381 is fixed,
we don't need to preserve spec compatibility with RHEL 8.

[skip changelog]

python-tox.spec

@@ -1,5 +1,5 @@
 # Many tests are enabled by default
-%bcond_without tests
+%bcond tests 1
 # However, some tests are disabled by default, becasue they require:
 #  a) tested tox to be installed and/or
 #  b) internet connection
@@ -11,7 +11,7 @@
 #  3) Build again --with ci_tests (and internet connection)
 #     (e.g. fedpkg mockbuild --no-clean-all --enable-network --with ci_tests)
 # The Fedora CI tests do this.
-%bcond_with ci_tests
+%bcond ci_tests 0
 
 # Unset -s on python shebang - ensure that extensions installed with pip
 # to user locations are seen and properly loaded