IPA: fix handling of certmap_ctx This patch fixes a use-after-free in the AD provider part and initializes the certmap_ctx with data from the cache at startup. Related to https://pagure.io/SSSD/sssd/issue/3508 Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com> Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>