aaa: exceptions should be propagated in builtin ldap provider

All exceptions which are caught during the privileged action execution
should be propagated and not swollowed.

In addition, NegativeArraySizeException is handled as a severe exception,
meaning there will be no attempt to try the next server if is caught

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1165721
Change-Id: Iafa1dcf67545e81a14981bb3c33e52a570684d72
Topic: AAA
Signed-off-by: Yair Zaslavsky <yzaslavs@redhat.com>