commit in : https://github.com/MariaDB/mariadb-connector-j/tree/feature/CONJ-366, waiting for MDEV-9059 validation

Benchmark done to test solution with pipeline (send-send-send then read-read-read) based on assumption that there won't be error/plugins change.

benchmark tested on distant server (local server doesn't really show any difference)

Benchmark                 Mode  Cnt     Score    Error  Units

connect.pipeline          avgt  100   349,047 ±  3,352  ms/op //new solution

connect.pipelineFail      avgt  100   461,312 ±  5,756  ms/op //new solution when pipeline fail (authentication plugin required), then redo without

connect.comMultiAuth      avgt  100   354,806 ±  4,664  ms/op //MDEV-9059

connect.standard          avgt  100   575,437 ±  9,173  ms/op // current 1.5.9 connection

connect.mysqlDriver       avgt  100  1183,953 ± 30,258  ms/op //mysql 5.1.40 driver

So solution work faster than implementing a specific protocol in server, and permit to have that on previous mariadb server / mysql server as well.

reopen issue since pipelining solution has some flaws.
Additionnal data query will wait for complete authentication to avoid any flaws.