[api] fixes csv features upload to save features as is_legacy=true for correct puvspr.dat generation [MRXN23-279]

[yulia-bel]

Fix saving features uploaded with cs file

Overview

Small fix that sets new features, uploaded with csv file, to have value is_legacy=true. After csv feature upload project sources has already been being set to legacy_import. Setting features as legacy was missing for correct data generation made by PuvsprDatLegacyProject.getAmountPerPlanningUnitAndFeature()

Designs

Link to the related design prototypes (if applicable)

Testing instructions

Upload features from csv file to a projects scenario. New features must have is_legacy=true in (apiDB).featuresTable.
Generating puvspr.dat file must return amounts per species per planning units in accordance with csv file data (not an empty table as it is now).

Feature relevant tickets

Link to the related task manager tickets

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Checklist before submitting

• Meaningful commits and code rebased on develop.
• If this PR adds feature that should be tested for regressions when
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  to the deploy checklist (docs/deployment-checklist.md)
• Update CHANGELOG file