[freeipa PR#4499][opened] [Backport][ipa-4-8] ipatests: move ipa_backup to tasks

[fcami]

   URL: https://github.com/freeipa/freeipa/pull/4499
Author: fcami
 Title: #4499: [Backport][ipa-4-8] ipatests: move ipa_backup to tasks
Action: opened

PR body:
"""
MANUAL BACKPORT of https://github.com/freeipa/freeipa/pull/4489 (straight cherry-pick, no
merge required)

* tasks had an ipa_backup() method that was not used anywhere.
* test_backup_and_restore had a backup() method that used to return
  both the path to the backup and the whole result from run_command ;
  The path to the backup can be determined from the result.

Clean up:
* move test_backup_and_restore.backup to tasks.ipa_backup, replacing
  the unused method.
* add tasks.get_backup_dir(host) which runs ipa-backup on host and
  returns the path to the backup directory.
* adjust test_backup_and_restore and test_replica_promotion.

Related: https://pagure.io/freeipa/issue/8217
Signed-off-by: François Cami <fcami(a)redhat.com&gt;
Reviewed-By: Michal Polovka <mpolovka(a)redhat.com&gt;
Reviewed-By: Rob Crittenden <rcritten(a)redhat.com&gt;
"""

To pull the PR as Git branch:
git remote add ghfreeipa https://github.com/freeipa/freeipa
git fetch ghfreeipa pull/4499/head:pr4499
git checkout pr4499