Trigger: implement rewriteLVL1 feature in CA

Migrate the rewriteLVL modifier to CA. But instead of introducing yet another flag, we assume that when the LVL1 simulation (Trigger.doLVL1) and BS-writing (Trigger.writeBS) is enabled, we always want to write out the updated LVL1 result.

In order for this to work in athenaHLT a few additional changes were required:

• Enable BS-writing by default.
• Peek into globals if doL1Sim is set. This could be avoided if all ART tests are migrated to set flags.Trigger.doLVL1 directly.
• Set default EDMVersion=3.

Relates to ATR-26582.