ipareplica: Refactor CA file handling

replicainstall.install_ca_cert has been removed, paths.IPA_CERTUPDATE is
called instead if the client was configured before deploying with
iparepica role.

FreeIPA commit 8f25b2a74a587548976f3d29f0b69d566d70125d

    Refactor CA file handling in replica installer

    Clean up and remove obsolete code from ipa-replica-install. For several
    versions replica installer first ensures that a host is an IPA client,
    then promotes the client to a replica. The client installer code sets up
    CA stores like IPA_CA_CRT already.