chore(license): add Apache 2.0 header to new test

Add the standard copyright/license header to `AzureVectorStoreMetadataTests`
to satisfy Spring’s checkstyle and spring-javaformat requirements.
No functional changes.

Signed-off-by: Jinwoo Lee <[email protected]>

Author: jinlee1703

vector-stores/spring-ai-azure-store/src/test/java/org/springframework/ai/vectorstore/azure/AzureVectorStoreMetadataTests.java

@@ -1,3 +1,19 @@
+/*
+ * Copyright 2023-2024 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package org.springframework.ai.vectorstore.azure;
 
 import static org.assertj.core.api.Assertions.assertThat;