[DISCUSS][2.0] FLIP-350: Remove query parameters from Jar handlers

[Chesnay Schepler]

The jar handlers currently accept a variety of parameters both as query 
parameters and via the request body.

While it is primarily a problem for sending program args as query 
parameters, because it's a nightmare with escaping parameters, the 
remaining parameters should follow suite for consistency.

https://cwiki.apache.org/confluence/display/FLINK/FLIP-350%3A+Remove+query+parameters+from+Jar+handlers