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.

/reviewed-on nexedi/slapos.core!140

slapos/slap/standalone.py

@@ -102,7 +102,7 @@ class SupervisorConfigWriter(ConfigWriter):
         stdout_logfile_maxbytes = 5MB
         stdout_logfile_backups = 10
 
-    """.format(**locals()))
+    """).format(**locals())
 
   def _getSupervisorConfigParts(self):
     """Iterator on parts of formatted config.
@@ -129,7 +129,7 @@ class SupervisorConfigWriter(ConfigWriter):
         startretries = 0
         startsecs = 0
         redirect_stderr = true
-        """.format(**locals()))
+        """).format(**locals())
 
     for program, program_config in standalone_slapos._slapos_commands.items():
       yield self._getProgramConfig(
@@ -173,7 +173,7 @@ class SlapOSConfigWriter(ConfigWriter):
               host = {standalone_slapos._server_ip}
               port = {standalone_slapos._server_port}
               database_uri = {standalone_slapos._proxy_database}
-              """.format(**locals())))
+              """).format(**locals()))
 
 
 class SlapOSCommandWriter(ConfigWriter):
@@ -188,7 +188,7 @@ class SlapOSCommandWriter(ConfigWriter):
               SLAPOS_CONFIGURATION={self._standalone_slapos._slapos_config} \\
               SLAPOS_CLIENT_CONFIGURATION=$SLAPOS_CONFIGURATION \\
               exec slapos "$@"
-      """.format(**locals())))
+      """).format(**locals()))
     os.chmod(path, 0o755)