Update sync chain info on own block import (#6424)

Before we only updated the chain info of sync when we have imported
something using the import queue. However, if you import your own
blocks, this is not done using the import queue and so sync is not
updated. If we don't do this, it can lead to sync switching to "major
sync" mode because sync is not informed about new blocks. This
especially happens on Cumulus, where a collator is selected multiple
times to include its block into the relay chain and thus, sync switches
to major sync mode while the node is still building blocks.