fix(bigtableadmin): update the API

#### bigtableadmin:v2

The following keys were changed:
- resources.operations.resources.projects.resources.operations.methods.list.parameters.returnPartialSuccess.description
- schemas.ListOperationsResponse.properties.unreachable.description

Author: yoshi-automation

discovery/bigtableadmin-v2.json

@@ -201,7 +201,7 @@
                       "type": "string"
                     },
                     "returnPartialSuccess": {
-                      "description": "When set to `true`, operations that are reachable are returned as normal, and those that are unreachable are returned in the [ListOperationsResponse.unreachable] field. This can only be `true` when reading across collections e.g. when `parent` is set to `\"projects/example/locations/-\"`. This field is not by default supported and will result in an `UNIMPLEMENTED` error if set unless explicitly documented otherwise in service or product specific documentation.",
+                      "description": "When set to `true`, operations that are reachable are returned as normal, and those that are unreachable are returned in the ListOperationsResponse.unreachable field. This can only be `true` when reading across collections. For example, when `parent` is set to `\"projects/example/locations/-\"`. This field is not supported by default and will result in an `UNIMPLEMENTED` error if set unless explicitly documented otherwise in service or product specific documentation.",
                       "location": "query",
                       "type": "boolean"
                     }
@@ -3118,7 +3118,7 @@
       }
     }
   },
-  "revision": "20251026",
+  "revision": "20251209",
   "rootUrl": "https://bigtableadmin.googleapis.com/",
   "schemas": {
     "AppProfile": {
@@ -4942,7 +4942,7 @@
           "type": "array"
         },
         "unreachable": {
-          "description": "Unordered list. Unreachable resources. Populated when the request sets `ListOperationsRequest.return_partial_success` and reads across collections e.g. when attempting to list all resources across all supported locations.",
+          "description": "Unordered list. Unreachable resources. Populated when the request sets `ListOperationsRequest.return_partial_success` and reads across collections. For example, when attempting to list all resources across all supported locations.",
           "items": {
             "type": "string"
           },

src/apis/bigtableadmin/v2.ts

@@ -1447,7 +1447,7 @@ export namespace bigtableadmin_v2 {
      */
     operations?: Schema$Operation[];
     /**
-     * Unordered list. Unreachable resources. Populated when the request sets `ListOperationsRequest.return_partial_success` and reads across collections e.g. when attempting to list all resources across all supported locations.
+     * Unordered list. Unreachable resources. Populated when the request sets `ListOperationsRequest.return_partial_success` and reads across collections. For example, when attempting to list all resources across all supported locations.
      */
     unreachable?: string[] | null;
   }
@@ -2461,7 +2461,7 @@ export namespace bigtableadmin_v2 {
      *     pageSize: 'placeholder-value',
      *     // The standard list page token.
      *     pageToken: 'placeholder-value',
-     *     // When set to `true`, operations that are reachable are returned as normal, and those that are unreachable are returned in the [ListOperationsResponse.unreachable] field. This can only be `true` when reading across collections e.g. when `parent` is set to `"projects/example/locations/-"`. This field is not by default supported and will result in an `UNIMPLEMENTED` error if set unless explicitly documented otherwise in service or product specific documentation.
+     *     // When set to `true`, operations that are reachable are returned as normal, and those that are unreachable are returned in the ListOperationsResponse.unreachable field. This can only be `true` when reading across collections. For example, when `parent` is set to `"projects/example/locations/-"`. This field is not supported by default and will result in an `UNIMPLEMENTED` error if set unless explicitly documented otherwise in service or product specific documentation.
      *     returnPartialSuccess: 'placeholder-value',
      *   });
      *   console.log(res.data);
@@ -2591,7 +2591,7 @@ export namespace bigtableadmin_v2 {
      */
     pageToken?: string;
     /**
-     * When set to `true`, operations that are reachable are returned as normal, and those that are unreachable are returned in the [ListOperationsResponse.unreachable] field. This can only be `true` when reading across collections e.g. when `parent` is set to `"projects/example/locations/-"`. This field is not by default supported and will result in an `UNIMPLEMENTED` error if set unless explicitly documented otherwise in service or product specific documentation.
+     * When set to `true`, operations that are reachable are returned as normal, and those that are unreachable are returned in the ListOperationsResponse.unreachable field. This can only be `true` when reading across collections. For example, when `parent` is set to `"projects/example/locations/-"`. This field is not supported by default and will result in an `UNIMPLEMENTED` error if set unless explicitly documented otherwise in service or product specific documentation.
      */
     returnPartialSuccess?: boolean;
   }