feat: remove @BetaApi annotations from get/setDatabaseId methods (#1277)

Cherry pick of #1272

Author: kolea2

google-cloud-datastore/src/main/java/com/google/cloud/datastore/BaseKey.java

@@ -20,7 +20,6 @@
 import static com.google.cloud.datastore.Validator.validateNamespace;
 import static com.google.cloud.datastore.Validator.validateProjectId;
 
-import com.google.api.core.BetaApi;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
@@ -117,7 +116,6 @@ public B setNamespace(String namespace) {
     }
 
     /** Sets the database id of the key. */
-    @BetaApi
     public B setDatabaseId(String databaseId) {
       this.databaseId = databaseId;
       return self();
@@ -148,7 +146,6 @@ public String getNamespace() {
     return namespace;
   }
 
-  @BetaApi
   public String getDatabaseId() {
     return databaseId;
   }

google-cloud-datastore/src/main/java/com/google/cloud/datastore/DatastoreOptions.java

@@ -19,7 +19,6 @@
 import static com.google.cloud.datastore.Validator.validateNamespace;
 import static com.google.cloud.datastore.spi.v1.DatastoreRpc.Transport.GRPC;
 
-import com.google.api.core.BetaApi;
 import com.google.cloud.ServiceDefaults;
 import com.google.cloud.ServiceOptions;
 import com.google.cloud.ServiceRpc;
@@ -112,7 +111,6 @@ public Builder setNamespace(String namespace) {
       return this;
     }
 
-    @BetaApi
     public Builder setDatabaseId(String databaseId) {
       this.databaseId = databaseId;
       return this;
@@ -176,7 +174,6 @@ public String getNamespace() {
     return namespace;
   }
 
-  @BetaApi
   public String getDatabaseId() {
     return this.databaseId;
   }

google-cloud-datastore/src/main/java/com/google/cloud/datastore/IncompleteKey.java

@@ -16,7 +16,6 @@
 
 package com.google.cloud.datastore;
 
-import com.google.api.core.BetaApi;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import java.util.List;
@@ -107,7 +106,6 @@ public static Builder newBuilder(String projectId, String kind) {
     return new Builder(projectId, kind);
   }
 
-  @BetaApi
   public static Builder newBuilderWithDatabaseId(String projectId, String kind, String databaseId) {
     return new Builder(projectId, kind, databaseId);
   }

google-cloud-datastore/src/main/java/com/google/cloud/datastore/Key.java

@@ -18,7 +18,6 @@
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 
-import com.google.api.core.BetaApi;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.protobuf.TextFormat;
@@ -180,7 +179,6 @@ public static Builder newBuilder(String projectId, String kind, String name) {
     return new Builder(projectId, kind, name);
   }
 
-  @BetaApi
   public static Builder newBuilder(String projectId, String kind, String name, String databaseId) {
     return new Builder(projectId, kind, name, databaseId);
   }
@@ -189,7 +187,6 @@ public static Builder newBuilder(String projectId, String kind, long id) {
     return new Builder(projectId, kind, id);
   }
 
-  @BetaApi
   public static Builder newBuilder(String projectId, String kind, long id, String databaseId) {
     return new Builder(projectId, kind, id, databaseId);
   }

google-cloud-datastore/src/main/java/com/google/cloud/datastore/KeyFactory.java

@@ -16,7 +16,6 @@
 
 package com.google.cloud.datastore;
 
-import com.google.api.core.BetaApi;
 import com.google.common.collect.ImmutableList;
 
 /**
@@ -37,7 +36,6 @@ public KeyFactory(String projectId, String namespace) {
     this(projectId, namespace, "");
   }
 
-  @BetaApi
   public KeyFactory(String projectId, String namespace, String databaseId) {
     super(projectId);
     setNamespace(namespace);

google-cloud-datastore/src/main/java/com/google/cloud/datastore/testing/RemoteDatastoreHelper.java

@@ -16,7 +16,6 @@
 
 package com.google.cloud.datastore.testing;
 
-import com.google.api.core.BetaApi;
 import com.google.api.core.InternalApi;
 import com.google.api.gax.retrying.RetrySettings;
 import com.google.cloud.datastore.Datastore;
@@ -79,7 +78,6 @@ public static RemoteDatastoreHelper create() {
   }
 
   /** Creates a {@code RemoteStorageHelper} object. */
-  @BetaApi
   public static RemoteDatastoreHelper create(String databaseId) {
     HttpTransportOptions transportOptions = DatastoreOptions.getDefaultHttpTransportOptions();
     transportOptions =