remove support for old-format services ledger and RSS service plan #4579
Description
In #4466 we're changing the format of the sled agent services ledger and the RSS service plan. There's code (and tests) to support migration for existing systems. Once all deployments that we care about are running bits with #4466 in them (which looks like it'll be release 5 or 6), we should consider removing this migration code and the associated tests. As of now, the deployments we care about are probably the customer systems, plus dogfood and rack3, and I expect they'd all be updated in the next month or two.
Originally posted by @smklein in #4466 (comment)