chore(deps): upgrade gapic-generator-java to 2.8.0 and update gax-jav…

…a to 2.18.1 (#652)

- [ ] Regenerate this pull request now.

PiperOrigin-RevId: 450543911

Source-Link: googleapis/googleapis@5528344

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

java-mediatranslation/google-cloud-mediatranslation/src/main/java/com/google/cloud/mediatranslation/v1beta1/SpeechTranslationServiceClient.java

@@ -126,7 +126,6 @@ public static final SpeechTranslationServiceClient create(
    * Constructs an instance of SpeechTranslationServiceClient, using the given stub for making
    * calls. This is for advanced usage - prefer using create(SpeechTranslationServiceSettings).
    */
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public static final SpeechTranslationServiceClient create(SpeechTranslationServiceStub stub) {
     return new SpeechTranslationServiceClient(stub);
   }
@@ -142,7 +141,6 @@ protected SpeechTranslationServiceClient(SpeechTranslationServiceSettings settin
     this.stub = ((SpeechTranslationServiceStubSettings) settings.getStubSettings()).createStub();
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   protected SpeechTranslationServiceClient(SpeechTranslationServiceStub stub) {
     this.settings = null;
     this.stub = stub;
@@ -152,7 +150,6 @@ public final SpeechTranslationServiceSettings getSettings() {
     return settings;
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public SpeechTranslationServiceStub getStub() {
     return stub;
   }

java-mediatranslation/google-cloud-mediatranslation/src/main/java/com/google/cloud/mediatranslation/v1beta1/stub/SpeechTranslationServiceStubSettings.java

@@ -97,7 +97,6 @@ public class SpeechTranslationServiceStubSettings
     return streamingTranslateSpeechSettings;
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public SpeechTranslationServiceStub createStub() throws IOException {
     if (getTransportChannelProvider()
         .getTransportName()