Farm env: Collect correct values for farm

[iLLiCiTiT]

Changelog Description

Actually collect valid values for farm environment variables.

Additional info

The plugin did use values from os.environ but most of the values are not set in env variables, or it should not be based on env variables.

• AYON_USERNAME - is not filled in os.environ
• AYON project/folder/task - should be filled from context data instead of os.environ
• AYON_LOG_NO_COLORS - should be forced to be "1" for farm

Testing notes:

1. The values under farm key are correct.