kdump-lib.sh: kdump_get_arch_recommend_size uses crashkernel.default
    
    Resolves: bz1986281
    Conflict: None
    Upstream: Fedora
    
    commit 7b7ddaba88af9bcbbcc3d219e1c7f00b3a61152d
    Author: Kairui Song <kasong@redhat.com>
    Date:   Fri Jul 2 01:31:26 2021 +0800
    
        kdump-lib.sh: kdump_get_arch_recommend_size uses crashkernel.default
    
        The new `crashkernel.default` file in kernel package can be used as the
        ck_cmdline source.
    
        Also keep the legacy code so old kernel packages will still work.
    
        Signed-off-by: Kairui Song <kasong@redhat.com>
        Acked-by: Pingfan Liu <piliu@redhat.com>
    
    Signed-off-by: Kairui Song <kasong@redhat.com>