Introduce non_tls event for legacy python Thrift servers
Introduce non_tls event for legacy python Thrift servers

Summary: [`TCppServer`](https://www.internalfb.com/code/fbsource/[74e5c8894b99]/fbcode/thrift/lib/py/server/TCppServer.py?lines=232%2C239) is the legacy python interop with C++'s `ThriftServer`. It explicitly sets `SSLPolicy` to `PERMITTED` so plaintext connections get logged to `non_tls.manual_policy` which is very highly sampled.

Reviewed By: AjanthanAsogamoorthy

Differential Revision: D33520962

fbshipit-source-id: 92d9695a49ab73d66cc9c928f1ebe5947ad43929

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