chore: Integrate new gapic-generator-java and rules_gapic (#748)

- [ ] Regenerate this pull request now.

PiperOrigin-RevId: 454027580

Source-Link: googleapis/googleapis@1b22277

Source-Link: googleapis/googleapis-gen@e04cea2
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiZTA0Y2VhMjBkMGQxMmViNWMzYmRiMzYwYTllNzJiNjU0ZWRjYjYzOCJ9

chore(deps): upgrade gapic-generator-java to 2.8.0 and update gax-java to 2.18.1
PiperOrigin-RevId: 450543911

Source-Link: googleapis/googleapis@5528344

Source-Link: googleapis/googleapis-gen@9f6775c
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiOWY2Nzc1Y2FiMTk1ODk4MmI4ODk2N2E0M2U1ZTgwNmFmMGYxMzVkYiJ9

java-cloudbuild/google-cloud-build/src/main/java/com/google/cloud/devtools/cloudbuild/v1/CloudBuildClient.java

@@ -18,7 +18,6 @@
 
 import com.google.api.core.ApiFuture;
 import com.google.api.core.ApiFutures;
-import com.google.api.core.BetaApi;
 import com.google.api.gax.core.BackgroundResource;
 import com.google.api.gax.longrunning.OperationFuture;
 import com.google.api.gax.paging.AbstractFixedSizeCollection;
@@ -168,7 +167,6 @@ public static final CloudBuildClient create(CloudBuildSettings settings) throws
    * Constructs an instance of CloudBuildClient, using the given stub for making calls. This is for
    * advanced usage - prefer using create(CloudBuildSettings).
    */
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public static final CloudBuildClient create(CloudBuildStub stub) {
     return new CloudBuildClient(stub);
   }
@@ -183,7 +181,6 @@ protected CloudBuildClient(CloudBuildSettings settings) throws IOException {
     this.operationsClient = OperationsClient.create(this.stub.getOperationsStub());
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   protected CloudBuildClient(CloudBuildStub stub) {
     this.settings = null;
     this.stub = stub;
@@ -194,7 +191,6 @@ public final CloudBuildSettings getSettings() {
     return settings;
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public CloudBuildStub getStub() {
     return stub;
   }
@@ -537,7 +533,7 @@ public final UnaryCallable<ListBuildsRequest, ListBuildsPagedResponse> listBuild
    *           .build();
    *   while (true) {
    *     ListBuildsResponse response = cloudBuildClient.listBuildsCallable().call(request);
-   *     for (Build element : response.getResponsesList()) {
+   *     for (Build element : response.getBuildsList()) {
    *       // doThingsWith(element);
    *     }
    *     String nextPageToken = response.getNextPageToken();
@@ -1272,7 +1268,7 @@ public final ListBuildTriggersPagedResponse listBuildTriggers(ListBuildTriggersR
    *   while (true) {
    *     ListBuildTriggersResponse response =
    *         cloudBuildClient.listBuildTriggersCallable().call(request);
-   *     for (BuildTrigger element : response.getResponsesList()) {
+   *     for (BuildTrigger element : response.getTriggersList()) {
    *       // doThingsWith(element);
    *     }
    *     String nextPageToken = response.getNextPageToken();
@@ -2292,7 +2288,7 @@ public final ListWorkerPoolsPagedResponse listWorkerPools(ListWorkerPoolsRequest
    *           .build();
    *   while (true) {
    *     ListWorkerPoolsResponse response = cloudBuildClient.listWorkerPoolsCallable().call(request);
-   *     for (WorkerPool element : response.getResponsesList()) {
+   *     for (WorkerPool element : response.getWorkerPoolsList()) {
    *       // doThingsWith(element);
    *     }
    *     String nextPageToken = response.getNextPageToken();

java-cloudbuild/google-cloud-build/src/main/java/com/google/cloud/devtools/cloudbuild/v1/stub/CloudBuildStubSettings.java

@@ -479,7 +479,6 @@ public UnaryCallSettings<UpdateWorkerPoolRequest, Operation> updateWorkerPoolSet
     return listWorkerPoolsSettings;
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public CloudBuildStub createStub() throws IOException {
     if (getTransportChannelProvider()
         .getTransportName()