http: do not treat FTPS over CONNECT as HTTPS

If we use FTPS over CONNECT, the TLS handshake for the FTPS control
connection needs to be initiated in the SENDPROTOCONNECT state, not
the WAITPROXYCONNECT state.  Otherwise, if the TLS handshake completed
without blocking, the information about the completed TLS handshake
would be saved to a wrong flag.  Consequently, the TLS handshake would
be initiated in the SENDPROTOCONNECT state once again on the same
connection, resulting in a failure of the TLS handshake.  I was able to
observe the failure with the NSS backend if curl ran through valgrind.

Note that this commit partially reverts curl-7_21_6-52-ge34131db.