BREAKING CHANGE: Removing remote integration feature (#17001)

## Context
The feature has not been maintained for more than a year and was never
officially launched.
This PR removes its code due to the upcoming refactoring of the
sync-metadata that will break its logic if not handled properly and it
would be too costly for the time being.

TODO:
- remove isRemote from object/field metadata

packages/twenty-server/src/engine/twenty-orm/entity-manager/workspace-entity-manager.spec.ts

@@ -207,9 +207,6 @@ describe('WorkspaceEntityManager', () => {
         'test-entity': 'test-entity-id',
       },
       featureFlagsMap: {
-        IS_AIRTABLE_INTEGRATION_ENABLED: false,
-        IS_POSTGRESQL_INTEGRATION_ENABLED: false,
-        IS_STRIPE_INTEGRATION_ENABLED: false,
         IS_UNIQUE_INDEXES_ENABLED: false,
         IS_JSON_FILTER_ENABLED: false,
         IS_AI_ENABLED: false,
@@ -236,9 +233,6 @@ describe('WorkspaceEntityManager', () => {
 
     mockDataSource = {
       featureFlagMap: {
-        IS_AIRTABLE_INTEGRATION_ENABLED: false,
-        IS_POSTGRESQL_INTEGRATION_ENABLED: false,
-        IS_STRIPE_INTEGRATION_ENABLED: false,
         IS_UNIQUE_INDEXES_ENABLED: false,
         IS_JSON_FILTER_ENABLED: false,
         IS_AI_ENABLED: false,