tls13secretstest.c: add dummy test function #1272

Job	Run time
run-checker (no-cmp)	1m 11s
run-checker (no-cms)	1m 22s
run-checker (no-dgram)	1m 12s
run-checker (no-dh)	1m 11s
run-checker (no-dtls)	1m 19s
run-checker (no-ec)	1m 12s
run-checker (no-ecx)	1m 16s
run-checker (no-http)	1m 12s
run-checker (no-legacy enable-unstable-qlog)	1m 16s
run-checker (no-sock)	1m 10s
run-checker (enable-ssl-trace)	1m 15s
run-checker (no-stdio)	1m 8s
run-checker (no-threads)	1m 14s
run-checker (no-thread-pool)	1m 14s
run-checker (no-default-thread-pool)	1m 16s
run-checker (no-tls)	1m 25s
run-checker (no-tls1_2)	1m 17s
run-checker (no-tls1_3)	1m 46s
run-checker (enable-trace enable-fips)	1m 22s
run-checker (no-ui)	1m 16s
run-checker (no-quic)	1m 15s
	26m 49s

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