feat(jans-linux-setup): uninstall flex packages

As for removing jans via package manager, we need similar process for removing flex package.
In uninstall script we need to execute two commands:

```
python3 /opt/jans/jans-setup/flex/flex-linux-setup/flex_setup.py --remove-flex --no-restart-services --flex-non-interactive
python3 /opt/jans/jans-setup/install.py -uninstall -yes --keep-downloads --keep-setup
```
When we do these, package manager can cleanly uninstall flex, such as:
`zypper remove flex`