enable service integration test target for rhel8 beta (#48939)

Signed-off-by: Adam Miller <admiller@redhat.com>

test/integration/targets/service/aliases

@@ -3,4 +3,3 @@ shippable/posix/group1
 skip/freebsd
 skip/osx
 systemd
-skip/rhel8.0

test/integration/targets/service/tasks/main.yml

@@ -21,7 +21,7 @@
     - name: detect systemd init system
       set_fact:
         service_type: systemd
-      when: (ansible_distribution in ['RedHat', 'CentOS', 'ScientificLinux'] and ( ansible_distribution_version is version('7', '>=') and ansible_distribution_version is version('8', '<'))) or ansible_distribution == 'Fedora' or (ansible_distribution == 'Ubuntu' and ansible_distribution_version is version('15.04', '>=')) or (ansible_distribution == 'Debian' and ansible_distribution_version is version('8', '>=')) or ansible_os_family == 'Suse'
+      when: (ansible_distribution in ['RedHat', 'CentOS', 'ScientificLinux'] and ansible_distribution_major_version is version('7', '>=')) or ansible_distribution == 'Fedora' or (ansible_distribution == 'Ubuntu' and ansible_distribution_version is version('15.04', '>=')) or (ansible_distribution == 'Debian' and ansible_distribution_version is version('8', '>=')) or ansible_os_family == 'Suse'
     - name: detect upstart init system
       set_fact:
         service_type: upstart