Clean out old migration code and drupal id migration field. (#4340)

hypha/apply/activity/management/commands/migrate_comments.py

hypha/apply/categories/categories_seed.py

hypha/apply/categories/management/__init__.py

hypha/apply/categories/management/commands/__init__.py

...a/apply/categories/management/commands/seed_categories.py

hypha/apply/determinations/management/__init__.py

hypha/apply/determinations/management/commands/__init__.py

...ons/management/commands/migrate_concept_determinations.py

...ns/management/commands/migrate_proposal_determinations.py

.../determinations/migrations/0017_remove_drupal_id_field.py

hypha/apply/determinations/models.py

...management/commands/migrate_community_lab_applications.py

.../apply/funds/management/commands/migrate_concept_notes.py

...ly/funds/management/commands/migrate_concept_notes_502.py

...ly/funds/management/commands/migrate_concept_notes_503.py

...nds/management/commands/migrate_fellowship_application.py

...funds/management/commands/migrate_fellowship_proposals.py

hypha/apply/funds/management/commands/migrate_proposals.py

...pply/funds/management/commands/migrate_rr_applications.py

hypha/apply/funds/management/commands/migration_base.py