Revert documentation changes

doc/api/graphql/reference/index.md

@@ -630,7 +630,7 @@ Autogenerated return type of MarkAsSpamSnippet
 | `forceRemoveSourceBranch` | Boolean | Indicates if the project settings will lead to source branch deletion after merge |
 | `headPipeline` | Pipeline | The pipeline running on the branch HEAD of the merge request |
 | `id` | ID! | ID of the merge request |
-| `iid` | ID! | Internal ID of the merge request |
+| `iid` | String! | Internal ID of the merge request |
 | `inProgressMergeCommitSha` | String | Commit SHA of the merge request if merge is in progress |
 | `mergeCommitMessage` **{warning-solid}** | String | **Deprecated:** Renamed to defaultMergeCommitMessage |
 | `mergeCommitSha` | String | SHA of the merge request commit (set once merged) |
@@ -834,7 +834,7 @@ Information about pagination in a connection.
 | `duration` | Int | Duration of the pipeline in seconds |
 | `finishedAt` | Time | Timestamp of the pipeline's completion |
 | `id` | ID! | ID of the pipeline |
-| `iid` | ID! | Internal ID of the pipeline |
+| `iid` | String! | Internal ID of the pipeline |
 | `sha` | String! | SHA of the pipeline's commit |
 | `startedAt` | Time | Timestamp when the pipeline was started |
 | `status` | PipelineStatusEnum! | Status of the pipeline (CREATED, WAITING_FOR_RESOURCE, PREPARING, PENDING, RUNNING, FAILED, SUCCESS, CANCELED, SKIPPED, MANUAL, SCHEDULED) |