Migrate field type probability to rating

[FelixMalfait]

I saw in the code we have a field type "probability": https://github.com/twentyhq/twenty/blob/aa8d689e3e4a2a923dddd6c0b33ad458a127fa66/packages/twenty-server/src/metadata/field-metadata/field-metadata.entity.ts#L30

I don't think we should have both Probability and Rating. We should only keep one field type (probability)

Eventually this field type could have additional options to customize the display and values in the future

[charlesBochet]

Let's remove it!

[FelixMalfait]

OK I think this should be very quick (just a few lines of code to delete?), it doesn't seem to be used.

But Opportunity probability used to be of type rating I think? And now it's just a basic string? we should fix this and bring it back