server install: remove error log about missing bkup file

The client installer code can be called in 3 different ways:
- from ipa-client-install CLI
- from ipa-replica-install CLI if the client is not already installed
- from ipa-server-install

In the last case, the client installer is called with
options.on_master=True
As a result, it's skipping the part that is creating the krb5
configuration:
    if not options.on_master:
        nolog = tuple()
        configure_krb5_conf(...)

The configure_krb5_conf method is the place where the krb5.conf file is
backup'ed with the extention ".ipabkp". For a master installation, this
code is not called and the ipabkp file does not exist => delete raises
an error.

When delete fails because the file does not exist, no need to log an
error message.

Fixes: https://pagure.io/freeipa/issue/9306
Signed-off-by: Florence Blanc-Renaud <flo@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>

ipaclient/install/client.py

@@ -124,10 +124,9 @@ def cleanup(func):
             os.rmdir(ccache_dir)
         except OSError:
             pass
-        try:
-            os.remove(krb_name + ".ipabkp")
-        except OSError:
-            logger.error("Could not remove %s.ipabkp", krb_name)
+        # During master installation, the .ipabkp file is not created
+        # Ignore the delete error if it is "file does not exist"
+        remove_file(krb_name + ".ipabkp")
 
     return inner