Fix dtls timeout dead code

Fix dtls timeout dead code

Delete dtls timeout dead code in dtls1_handle_timeout

Fix: #15559

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Ben Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/16151)