chore(deps): upgrade gapic-generator-java to 2.8.0 and update gax-java to 2.18.1 (#887)

- [ ] Regenerate this pull request now.

PiperOrigin-RevId: 450543911

Source-Link: googleapis/googleapis@5528344

Source-Link: https://github.com/googleapis/googleapis-gen/commit/9f6775cab1958982b88967a43e5e806af0f135db
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiOWY2Nzc1Y2FiMTk1ODk4MmI4ODk2N2E0M2U1ZTgwNmFmMGYxMzVkYiJ9

Author: gcf-owl-bot[bot]

google-cloud-dlp/src/main/java/com/google/cloud/dlp/v2/DlpServiceClient.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.paging.AbstractFixedSizeCollection;
 import com.google.api.gax.paging.AbstractPage;
@@ -198,7 +197,6 @@ public static final DlpServiceClient create(DlpServiceSettings settings) throws
    * Constructs an instance of DlpServiceClient, using the given stub for making calls. This is for
    * advanced usage - prefer using create(DlpServiceSettings).
    */
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public static final DlpServiceClient create(DlpServiceStub stub) {
     return new DlpServiceClient(stub);
   }
@@ -212,7 +210,6 @@ protected DlpServiceClient(DlpServiceSettings settings) throws IOException {
     this.stub = ((DlpServiceStubSettings) settings.getStubSettings()).createStub();
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   protected DlpServiceClient(DlpServiceStub stub) {
     this.settings = null;
     this.stub = stub;
@@ -222,7 +219,6 @@ public final DlpServiceSettings getSettings() {
     return settings;
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public DlpServiceStub getStub() {
     return stub;
   }

google-cloud-dlp/src/main/java/com/google/cloud/dlp/v2/stub/DlpServiceStubSettings.java

@@ -711,7 +711,6 @@ public UnaryCallSettings<FinishDlpJobRequest, Empty> finishDlpJobSettings() {
     return finishDlpJobSettings;
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public DlpServiceStub createStub() throws IOException {
     if (getTransportChannelProvider()
         .getTransportName()