MAINT: remove unused imports

Signed-off-by: George Chen <[email protected]>

Author: chenqi0805

data-prepper-plugins/encryption-plugin/src/test/java/org/opensearch/dataprepper/plugins/encryption/EncryptionPluginTest.java

@@ -23,7 +23,6 @@
 import java.util.Optional;
 import java.util.Set;
 import java.util.UUID;
-import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 
 import static org.hamcrest.CoreMatchers.equalTo;

data-prepper-plugins/encryption-plugin/src/test/java/org/opensearch/dataprepper/plugins/encryption/S3BucketAndPrefixTest.java

@@ -13,7 +13,6 @@
 import java.util.stream.Stream;
 
 import static org.hamcrest.CoreMatchers.equalTo;
-import static org.hamcrest.CoreMatchers.nullValue;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.params.provider.Arguments.arguments;

data-prepper-plugins/encryption-plugin/src/test/java/org/opensearch/dataprepper/plugins/encryption/S3EncryptedDataKeyWriterTest.java

@@ -25,7 +25,6 @@
 
 import static org.hamcrest.CoreMatchers.endsWith;
 import static org.hamcrest.CoreMatchers.equalTo;
-import static org.hamcrest.CoreMatchers.startsWith;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.mockito.ArgumentMatchers.any;