Very small enhancements

[benoit74]

Changes

• Performance test HOWTO: Fix test DB name and remove typo
• Synthetic data generator: Move "now period" a little bit in the past so that we do not already have indicator periods for 2024 (now a problem with new backend logic)
• Fix some log levels:
  • all unexpected errors should be a WARNING
  • it is useful/harmless to display DB name in INFO (not just DEBUG)
• Add debug trace to know how long the computations are taking

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (3358478) 100.00% compared to head (2871320) 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #99 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 37 37 Lines 1100 1100 Branches 204 204 ========================================= Hits 1100 1100 ```

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