tls: move convertNPNProtocols to End-of-Life
This was deprecated in 10.0.0 because NPN support was removed. It does not make sense to keep this around longer than 10.x
/cc @bnoordhuis
Checklist
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make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines