[BE] Remove transformed_content_data

[karpov-aleksandr]

Remove transformed_content_data table and related deprecated endpoints:

• POST /api/v3/packages/{packageId}/versions/{version}/{apiType}/build/groups/{groupName}/buildType/{buildType}
• GET /api/v3/packages/{packageId}/versions/{version}/{apiType}/export/groups/{groupName}/buildType/{buildType}
  After that remove reducedSourceSpecifications and mergedSpecification as build types

[karpov-aleksandr]

Blocked by #518