mon: set the profile and ruleset defaults early

mon: set the profile and ruleset defaults early

The poolstr is removed from the prepare_pool_crush_ruleset prototype
because it no longer decides for the default ruleset, if it is not
omitted by the caller of osd pool create.

If no profile
  profile = default
If no ruleset and profile is default
  ruleset = erasure-code
If no ruleset and profile is not default
  ruleset = the name of the pool

Signed-off-by: Loic Dachary <loic@dachary.org>