test(logging): expose and reuse TEST_SINK_PREFIX from RemoteLoggingHelper

Exposes TEST_SINK_PREFIX as public constant in RemoteLoggingHelper and statically imports it directly into ITSinkTest, removing duplicate local constant declarations.

BUG=b/482174880
TAG=agy
CONV=d4a74f94-579a-4c3f-96c3-f90fcbc6c699

Author: lqiu96

java-logging/google-cloud-logging/src/main/java/com/google/cloud/logging/testing/RemoteLoggingHelper.java

@@ -37,7 +37,7 @@
 public class RemoteLoggingHelper {
 
   private static final Logger log = Logger.getLogger(RemoteLoggingHelper.class.getName());
-  private static final String TEST_SINK_PREFIX = "test-";
+  public static final String TEST_SINK_PREFIX = "test-";
   private final LoggingOptions options;
 
   private RemoteLoggingHelper(LoggingOptions options) {

java-logging/google-cloud-logging/src/test/java/com/google/cloud/logging/it/ITSinkTest.java

@@ -16,6 +16,7 @@
 
 package com.google.cloud.logging.it;
 
+import static com.google.cloud.logging.testing.RemoteLoggingHelper.TEST_SINK_PREFIX;
 import static com.google.cloud.logging.testing.RemoteLoggingHelper.formatForTest;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -38,8 +39,6 @@
 
 public class ITSinkTest extends BaseSystemTest {
 
-  private static final String TEST_SINK_PREFIX = "test-";
-
   @BeforeClass
   public static void setUp() {
     // Cleanup all stucked sinks if any