replace/update the steps of remote plan

[guazhang]

when reuse some steps of the remote plan, but other steps need be replaced or updated.
so could we plan to support it ?

remote plan A:

summary:  this is remote plan
discover:
    how: fmf
    filter: "tag: t1"
provision:
    how: minute
    image: rhel-8
execute:
    how: tmt

plan B reuse the remote plan and need update the provision step

provision:
    how: beaker
    image: rhel-9