update_ssh_config_guestfs: fix incorrect task privilege

This task does not require elevated privileges, so become: true is
unnecessary and can be removed. Its use was also causing the task to run
as root (the default become_user [1]), which led to the following error:

task path:
/home/cel/src/kdevops/buildbot-configs/playbooks/roles/
update_ssh_config_guestfs/tasks/main.yml:73
fatal: [localhost]: FAILED! => {
    "changed": false,
    "path": "/root/.ssh/config",
    "state": "absent"
}

MSG:

file (/root/.ssh/config) is absent, cannot continue

Ensure the task is only run when the conditions are appropiate, i.e.
when the file exists.

[1]
https://docs.ansible.com/ansible/latest/playbook_guide/
playbooks_privilege_escalation.html#become-directives

Fixes f301c9a ("guestfs: ensure right permissions for ssh config")

Reported-by: Chuck Lever <chuck.lever@oracle.com>
Closes: https://lore.kernel.org/all/b2fb6337-f737-4ab9-94a5-f6d5d94db749@oracle.com/
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Daniel Gomez <da.gomez@samsung.com>

Author: dagomez137

playbooks/roles/update_ssh_config_guestfs/tasks/main.yml

@@ -71,9 +71,7 @@
       Include ~/.ssh/config_kdevops_*
 
 - name: Ensure ~/.ssh/config permissions
-  become: true
-  become_flags: 'su - -c'
-  become_method: ansible.builtin.sudo
   ansible.builtin.file:
     path: ~/.ssh/config
     mode: "0600"
+  when: ssh_config.stat.exists