Fix fact set using ternary filter

When the set_fact module is used with the ternary filter the evaluated
condition must be surrounded in parentheses, otherwise the fact will
always be set to False.

While other uses of ternary within this role don't seem to be effected,
update them also for consistency and readability.

Change-Id: I4809ded8b6fe738f8fa700434739ee0b1f6d3af1
(cherry picked from commit 2f68deee89)

tasks/galera_install_apt.yml

@@ -77,7 +77,7 @@
   apt_repository:
     repo: "{{ galera_percona_xtrabackup_repo.repo }}"
     filename: "{{ galera_percona_xtrabackup_repo.filename | default(omit) }}"
-    state: "{{ use_percona_upstream | bool | ternary('present','absent') }}"
+    state: "{{ (use_percona_upstream | bool) | ternary('present','absent') }}"
   register: add_repos
   until: add_repos|success
   retries: 5

tasks/galera_running_check.yml

@@ -15,7 +15,7 @@
 
 - name: Set fact for extra arguments in MySQL commands
   set_fact:
-    mysql_extra_args: "{{ ansible_os_family == 'Debian' | ternary('--defaults-file=/etc/mysql/debian.cnf', '') }}"
+    mysql_extra_args: "{{ (ansible_os_family == 'Debian') | ternary('--defaults-file=/etc/mysql/debian.cnf', '') }}"
   tags:
     - galera-cluster-state-check
     - galera-bootstrap