refactor: 💡 remove grant_scope_id and its uses (#2325)

✅ Closes: https://hashicorp.atlassian.net/browse/ICU-13877

addons/api/addon/generated/models/role.js

@@ -22,12 +22,6 @@ export default class GeneratedRoleModel extends BaseModel {
   })
   description;
 
-  @attr('string', {
-    description:
-      "The scope to which this role applies.  Defaults to the role's scope.",
-  })
-  grant_scope_id;
-
   @attr('array', {
     description:
       "The scopes to which this role applies.  Defaults to the role's scope.",

addons/api/addon/models/role.js

@@ -33,15 +33,6 @@ export default class RoleModel extends GeneratedRoleModel {
    */
   @attr({ readOnly: true, emptyArrayIfMissing: true }) grant_strings;
 
-  /**
-   * Convenience for looking up the grant scope, if loaded.
-   */
-  get grantScope() {
-    return this.grant_scope_id
-      ? this.store.peekRecord('scope', this.grant_scope_id)
-      : null;
-  }
-
   /**
    * A list of IDs for principals of type `user`.
    * @type {string[]}