standalone: fix support of recursive slapos
When having more than one read_only_shared_part_list, the template was first rendered with indentation and then dedented, but since dedent only remove the common indentation, we ended up with slapos.cfg like this:
$ cat /data/slappart11_testnode/cqg/inst/test0-9/tmp/etc/slapos.cfg
[slapos]
software_root = /data/slappart11_testnode/cqg/inst/test0-9/tmp/soft
instance_root = /data/slappart11_testnode/cqg/inst/test0-9/tmp/inst
shared_part_list =
/srv/slapgrid/slappart11/srv/shared
/srv/slapgrid/slappart11/srv/testnode/cqg/shared
/data/slappart11_testnode/cqg/inst/test0-9/tmp/shared
master_url = http://10.0.12.198:46312
computer_id = local
root_check = False
First dedent, then render the template to prevent this issue. Apply this to other uses of textwrap.dedent for consistency.