Parallelize CI test execution for faster build times

[GeorgGrassler]

Problem

Currently, our GitHub CI tests run sequentially in a single job:

1. make lorentz
2. make ql
3. make performance_ql (PR only)
4. make par (PR only)

This results in longer CI times as tests wait for each other to complete.

Proposed Solution

Split tests into separate parallel jobs:

jobs:
  lorentz-test:
    runs-on: ubuntu-24.04
    steps: [build, run lorentz]
  
  ql-test:
    runs-on: ubuntu-24.04  
    steps: [build, run ql]
  
  performance-test:
    runs-on: ubuntu-24.04
    steps: [build, run performance_ql]
  
  par-test:
    runs-on: ubuntu-24.04
    steps: [build, run par]

Considerations

• Need to handle build artifacts sharing or duplicate builds
• Artifact collection will need updates for parallel jobs
• Test data cloning may need coordination
• Overall CI time should improve significantly

Current Workflow Files

• .github/workflows/test-on-pr.yml (lines 163-204)
• .github/workflows/unit-tests-coverage.yml (separate, already parallel)