Update user_attribute_ignore for LDAP Identity config

With a recent patch to keystone, the use of tenantId, tenant_id, and
default_project_id was normalized to reference default_project_id for
all cases internally and translate to the expected results at the
controller (v2.0 returns tenantId, v3 returns default_project_id).

Devstack must now properly ignore the expected mapped LDAP attribute
of 'default_project_id' instead of the old 'tenantId'.  Without this
fix devstack will fail when using the LDAP identity backend because
the 'default_project_id' has been made a special case that requires
the operator of a Openstack cloud to explicitly choose an attribute
to map 'default_project_id' to if storing that value is desired.
Without explicitly mapping that attribute and not having it in the
'user_attribute_ignore' config option, the user_creates can fail.

related-bug: 1219739
Change-Id: I1dd3719de50f6d0948b3a9743e32a03d0ac56b3c
Merge "Update user_attribute_ignore for LDAP Identity config"