Revert "storage_proxy: stop waiting for hints replay when node goes down"
Revert "storage_proxy: stop waiting for hints replay when node goes down"

This reverts commit 22e06ace2cd661d842c2fd0c64fa70da563d903d.

The upcoming HTTP API for waiting for hint replay will be restricted
to waiting for hints on the node handling the request, so we are
removing all infrastructure related to coordinating hint waiting -
therefore this commit needs to be reverted.

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla