crimson/osd/watch: don't print bufferlists

The bufferlists clutter the logs and don't infrom of anything useful:
```
DEBUG 2023-05-26 23:36:29,780 [shard 2] osd - send_completion sending notify replies: {notify_reply_t{watcher_gid=4220, watcher_cookie=139786421930752, bl=buffer::list(len=0,

)}, notify_reply_t{watcher_gid=4220, watcher_cookie=139786422032096, bl=buffer::list(len=0,

)}}
```

Signed-off-by: Matan Breizman <[email protected]>

Author: Matan-B

src/crimson/osd/watch.cc

@@ -231,8 +231,7 @@ bool notify_reply_t::operator<(const notify_reply_t& rhs) const
 std::ostream &operator<<(std::ostream &out, const notify_reply_t &rhs)
 {
   out << "notify_reply_t{watcher_gid=" << rhs.watcher_gid
-      << ", watcher_cookie=" << rhs.watcher_cookie
-      << ", bl=" << rhs.bl << "}";
+      << ", watcher_cookie=" << rhs.watcher_cookie << "}";
   return out;
 }