Revert cypher suite update

The changes of FLINK-9310 causes Flink to fail when sending data between TaskManagers as reported by a user [1]. The problem seems to be that Netty's SslHandler (v4.0.27) tries to allocate heap buffers when using a GCM enabled cypher suite. However, since we explicitly prohibit the allocation of heap buffers it fails. In later Netty versions, this behaviour seems to be fixed.

I propose to revert the changes of FLINK-9310 and set the default cypher algorithm to TLS_RSA_WITH_AES_128_CBC_SHA.

[1] http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/Flink-1-5-Job-fails-to-execute-in-multiple-taskmanagers-parallelism-gt-1-td22467.html