data_provider_be: got rid of duplicating SIGTERM handler
It was wrong to install two libtevent SIGTERM handlers both of which did
orderly_shutdown()->exit(). Naturally only one of the handlers was executed
(as process was terminated with exit()) and libtevent docs doesn't say
anything about order of execution. But chances are, be_process_finalize()
was executed first so default_quit() was not executed and main_ctx was not
freed.
Moreover there is just no reason to have separate be_process_finalize()
at all: default server handler default_quit() frees main_ctx. And be_ctx
is linked to main_ctx so will be freed by default handler as well.
Resolves: https://pagure.io/SSSD/sssd/issue/4088
Reviewed-by: Michal Židek <mzidek@redhat.com>