When we rollover and index we write the conditions of the rollover that
the old index met into the old index. Loading this index metadata
requires a working `NamedXContentRegistry` that has been populated with
parsers from the rollover infrastructure. We had a few loads that didn't
use a working `NamedXContentRegistry` and so would fail if they ever
encountered an index that had been rolled over. Here are the locations
of the loads and how I fixed them:
* IndexFolderUpgrader - removed entirely. It existed to support opening
indices made in Elasticsearch 2.x. Since we only need this change as far
back as 6.4.1 which will supports reading from indices created as far
back as 5.0.0 we should be good here.
* TransportNodesListGatewayStartedShards - wired the
`NamedXContentRegistry` into place.
* TransportNodesListShardStoreMetaData - wired the
`NamedXContentRegistry` into place.
* OldIndexUtils - removed entirely. It existed to support the zip based
index backwards compatibility tests which we've since replaced with code
that actually runs old versions of Elasticsearch.
In addition to fixing the actual problem I added full cluster restart
integration tests for rollover which would have caught this problem and
I added an extra assertion to IndexMetaData's deserialization code which
will trip if we try to deserialize and index's metadata without a fully
formed `NamedXContentRegistry`. It won't catch if use the *wrong*
`NamedXContentRegistry` but it is better than nothing.
Closes#33316
0d45752e50