tablets: Drop src vs dst equality check from move_tablet()

The code here looks like this

    if src.host == dst.host
        throw "Local migration not possible"

    if src == dst
        co_return;

The 2nd check is apparently never satisfied -- if src == dst this means
that src.host == dst.host and it should have thrown already

Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>

service/storage_service.cc

@@ -5747,10 +5747,6 @@ future<> storage_service::move_tablet(table_id table, dht::token token, locator:
             throw std::runtime_error("Migrating within the same node is not supported");
         }
 
-        if (src == dst) {
-            co_return;
-        }
-
         if (locator::contains(tinfo.replicas, dst.host)) {
             throw std::runtime_error(fmt::format("Tablet {} has replica on {}", gid, dst.host));
         }