src: drop CNNIC+StartCom certificate whitelisting

Remove the CNNIC certificates again and remove the whitelist from commit
3beb880 ("crypto: add cert check to CNNIC Whitelist") from June 2015.

Backport-PR-URL: #19633
PR-URL: #19322
Reviewed-By: Fedor Indutny <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Daniel Bevenius <[email protected]>
Reviewed-By: James M Snell <[email protected]>

Author: bnoordhuis