Reverse schema diff

[gak]

It appears that the schema diff direction is the reverse direction. The CI is checking for new local changes against production, but showing the "new" changes are the remote ones. In the case below, "new" is the existing production controller.

We should probably reverse this unless there's a use case in the other direction.

Another option could be to optionally specify both endpoints like the regular diff command.

export FTL_ENDPOINT=http://production
content=$(ftl schema diff || true)

Usage: ftl schema diff [<other-endpoint>] [flags]

Print any schema differences between this cluster and another cluster. Returns
an exit code of 1 if there are differences.

Arguments:
  [<other-endpoint>]    Other endpoint URL to compare against. If this is not
                        specified then ftl will perform a diff against the local
                        schema.