Replace failIfAlreadyExists variable with inline randomBoolean in S3 repository test

Author: kvanerum

modules/repository-s3/qa/third-party/src/test/java/org/elasticsearch/repositories/s3/S3RepositoryThirdPartyTests.java

@@ -264,7 +264,6 @@ public void testMultipartCopy() {
         // executeMultipart requires a minimum part size of 5 MiB
         final var blobBytes = randomBytesReference(randomIntBetween(5 * 1024 * 1024, 10 * 1024 * 1024));
         final var destinationBlobName = randomIdentifier();
-        final var failIfAlreadyExists = randomBoolean();
 
         final var repository = getRepository();
 
@@ -279,7 +278,7 @@ public void testMultipartCopy() {
                 sourceBlobName,
                 destinationBlobName,
                 blobBytes.length(),
-                failIfAlreadyExists
+                randomBoolean()
             );
 
             return destinationBlobContainer.readBlob(randomPurpose(), destinationBlobName).readAllBytes();