sc-informant: Do not show `Block history` if doing major sync (#14094)

After warp syncing a node it still downloads the block history. If the node is stopped and then
started later while downloading the block history, the node first needs to do a major sync to sync
to the tip of the chain. Before informant was showing `Block history` as sync state, while we
actually were doing a major sync. This pr is fixing this.