fix(data-export): File key uniqueness (#2821)

## Context

Current key generation does not allow to re-run service if there's any
failure after file being attached because of unique constraint on active
storage blobs table

## Description

Add salt to key generation to satisfy uniqueness during repeated runs

app/services/data_exports/combine_parts_service.rb

@@ -28,7 +28,7 @@ def call
         data_export.file.attach(
           io: tempfile,
           filename: data_export.filename,
-          key: "data_exports/#{data_export.id}.#{data_export.format}",
+          key: "data_exports/#{data_export.id}-#{SecureRandom.hex(5)}.#{data_export.format}",
           content_type: "text/csv"
         )
       end