This was added in Newton:
I97b72ae3e7e8ea3d6b596870d8da3aaa689fd6b5
And was meant to migrate keypairs from the cell
(nova) DB to the API DB. Before that though, the
keypairs per instance would be migrated to the
instance_extra table in the cell DB. The migration
to instance_extra was dropped in Queens with change:
Ie83e7bd807c2c79e5cbe1337292c2d1989d4ac03
As the commit message on ^ mentions, the 345 cell
DB schema migration required that the cell DB keypairs
table was empty before you could upgrade to Ocata.
The migrate_keypairs_to_api_db routine only migrates
any keypairs to the API DB if there are entries in the
keypairs table in the cell DB, but because of that blocker
migration in Ocata that cannot be the case anymore, so
really migrate_keypairs_to_api_db is just wasting time
querying the database during the online_data_migrations
routine without it actually migrating anything, so we
should just remove it.
Change-Id: Ie56bc411880c6d1c04599cf9521e12e8b4878e1e
Closes-Bug: #1822613
Matt Riedemann
cec1808050