Remove unused description column from common_third_parties

The description field was never surfaced in the UI and added no value.
Drop it from the database, Go structs, GraphQL schema, import tool,
frontend fragment, and vendor seed data.

Signed-off-by: Émile Ré <emile@getprobo.com>

pkg/server/api/console/v1/graphql/common_third_party.graphql

@@ -18,7 +18,6 @@ type CommonThirdParty
     ) {
     id: ID!
     name: String!
-    description: String
     category: VendorCategory!
     websiteUrl: String
     headquarterAddress: String