Get gridless test set to pass

[jluethi]

When trying to run the gridless test case UZH path: /data/active/fractal/Liberali/FractalTesting20220124/gridless_Yokogawa_recording-FMI/20220316_sec_FOCM_test-R1_E2/day3/TIF (number 4 of search first here: fractal-analytics-platform/fractal-client#213), the metadata parsing fails with the error message:
Exception: When parsing the Yokogawa mlf file, some sites had varying step size in Z. That is not supported for the OME-Zarr parsing

Let's check whether this is really the problem or whether something in the metadata parsing is failing for this file. Could be an issue when the metadata was created for this test set, could be a parsing problem.

[jluethi]

Digging into this, the problem again is float precision. In this case, the steps are of size 0.6 um. Thus, represented as floats. That means that sometimes they are 0.5999999999999979, sometimes they are 0.6000000000000014. I'll need to adapt the parsing to be robust against this.

[jluethi]

Test again now that #136 fixes the precision issue.

[jluethi]

With the metadata fix, the gridless search first now works as expected! 🎉
See 3f5c8b884683e881a6b07e058ef3b03348f9772e for the example

Overexposed (same image, but shows borders of FOVs):