:seedling: Remove unnecessary env variables in make target env-vars-for-wl-cluster

[michal-gubricky]

What this PR does / why we need it: Based on the introduction of local_mode feature(see issue #76). Some env variables are not needed when we are using local_mode. This commit adjust .envrc.sample and also remove these unnecessary env variables in make target env-vars-for-wl-cluster.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged): Fixes #100

TODOs:

• [ ] squash commits
• [ ] include documentation
• [ ] add unit tests