JVM options should not be hardcoded within the operator

[SrishT]

Description

Currently many JVM options are all hardcoded within the operator, which does not allow users to remove or modify the options added by the operator by default, even if they wish to do so.

Importance

must have

Location

pkg/controller/pravega/pravega_controller.go
pkg/controller/pravega/pravega_segmentstore.go

Suggestions for an improvement

The recommended JVM options along with their default values should be specified within the values.yaml file instead, so that the user can easily modify them if required.