Auto prescaler updates

Changes for the AutoPrescaler ATR-19313

• set an appropriate upload L1PSK username from variables available in the environment (will be AutoPrescaleEditor)
• hide keys generated by this user
• add l1only option for ExtractMenu to avoid downloading files not needed by the AP (or other L1 experts)

Tested at point 1 by using private patch area as part of AP tests: https://atlasop.cern.ch/elisa/display/461719

cc @aporeba @ballbroo

Additional unrelated fix for createReprKeys.py - missing env to ensure run as python (cc @palacino )