Send tip change notification from invalidateblock

This change is needed to prevent sync_blocks timeouts in the mempool_reorg
test after the sync_blocks update in the upcoming commit
"[qa] Change sync_blocks to pick smarter maxheight".

This change was initially suggested by Suhas Daftuar <sdaftuar@chaincode.com>
in https://github.com/bitcoin/bitcoin/pull/8680#r78209060