HLTSeeding: Migration to new L1Menu access + clean-up

• Migrate from using L1ConfigSvc to reading L1Menu from DetectorStore
• Simplify execution, stop relying on incidents and update configuration in start() where needed
• Remove a few obsolete classes dating back to early Run-3 development and not used anywhere today
• Remove obsolete code, move some code to base classes to reduce duplication
• Improve the code in a few places for readability (e.g. more explicit memory management)
• Fix a bug where tag&probe chains with L1_MU probe were not seeded on the probe leg in the phase-1 L1Muon path

cc @smh, @fwinkl, @tamartin, @tbold