Use the LHC orbit duration for CTP scaler rates

[sawenzel]

This fixes the orbit-to-time conversion in the CTP scaler rates.

• Rates used 88 us per orbit instead of 88.92 us, so they were 1.05 % too high.
• For run 569757 (2 colliding bunches) this put the TVX rate above the colliding-bunch rate.
• The conversion now uses o2::constants::lhc::LHCOrbitMUS, as getRatesForIndex already does.

https://its.cern.ch/jira/browse/O2-7064

[sawenzel]

This renders the IR of run physical:

┌──────────────────┬─────────┬──────────────┬───────────────────────────┬──────────────┐
  │       run        │ library │ mid-run rate │ intervals above the limit │ p at mid-run │
  ├──────────────────┼─────────┼──────────────┼───────────────────────────┼──────────────┤
  │ 569757           │ release │ 22587.2 Hz   │ 174 of 174                │ 1.00428      │
  ├──────────────────┼─────────┼──────────────┼───────────────────────────┼──────────────┤
  │ 569757           │ with this PR │ 22352.3 Hz   │ 0 of 174                  │ 0.99384      │
  ├──────────────────┼─────────┼──────────────┼───────────────────────────┼──────────────┤
  │ 571043 (control) │ release │ 501132.1 Hz  │ 0                         │ 0.02130      │
  ├──────────────────┼─────────┼──────────────┼───────────────────────────┼──────────────┤
  │ 571043 (control) │ with this PR │ 495921.6 Hz  │ 0                         │ 0.02108      │
  └──────────────────┴─────────┴──────────────┴───────────────────────────┴──────────────┘

[alibuild]

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