Make `ProtocolWarnings 1` less noisy to run

While investigating the right fix for #40175 (closed), Sebastian reminded me that we get lots of frequent protocol warnings. We should make these less frequent so that it's less of a burden to run Tor with protocol warnings enabled.

The most common warnings that Sebastian encountered are:

84853 Rejecting RENDEZVOUS1 cell with unrecognized rendezvous cookie
9975 Didn't recognize cell, but circ stops here
10002 circuit_receive_relay_cell (forward) failed

Options are:

Downgrade to INFO or DEBUG.
Add rate-limiting
Identify cases that truly should be protocol warnings, and downgrade or rate-limit the other cases.

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