BDB tuning should be applied only when BDB backend is used

389DS supports BDB and LMDB backends. FreeIPA installation fails with
LMDB backend since it tries to apply tuning for BDB backend.

Instead, tuning for BDB should be applied only when 389DS uses BDB
backend.

Fixes: https://pagure.io/freeipa/issue/9435

Signed-off-by: Viktor Ashirov <vashirov@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>

ipaserver/install/dsinstance.py

@@ -31,6 +31,7 @@
 from lib389.instance.options import General2Base, Slapd2Base
 from lib389.instance.remove import remove_ds_instance as lib389_remove_ds
 from lib389.instance.setup import SetupDs
+from lib389.utils import get_default_db_lib
 
 from ipalib import x509
 from ipalib.install import certmonger, certstore
@@ -227,7 +228,8 @@ def __init__(self, realm_name=None, domain_name=None, fstore=None,
     def __common_setup(self):
 
         self.step("creating directory server instance", self.__create_instance)
-        self.step("tune ldbm plugin", self.__tune_ldbm)
+        if get_default_db_lib() == 'bdb':
+            self.step("tune ldbm plugin", self.__tune_ldbm)
         if self.config_ldif is not None:
             self.step("stopping directory server", self.__stop_instance)
             self.step(