fix duplicated tasks in the ispmail-postfix role

[pyvain]

The ispmail-postfix role contains duplicated tasks which seem to originate from different versions of the playbook.

I suspect that merging some changes in the past did something funky.

This PR attempts to clean it up :

• It seems that you decided to regroup the use of templates in the first task. Therefore there is no need to re-use these templates for virtual mailbox, virtual alias and email-to-email later on. I removed the corresponding tasks.
• Restricting the access to the mappings containing passwords is also done when using the templates via the mode: 0640 argument. I removed the corresponding task.
• The postconf commands for rspamd are executed twice. I removed the superfluous ones. And fixed a quote mismatch in one of them.

Thank you for your awesome guide ! :slightly_smiling_face:

[pyvain]

I just noticed that postconf virtual_alias_maps= is also executed twice: without and with the email-to-email mapping. I suppose that the first one can be removed too, even if catchalls are not used.