fix: flaky test ClusterMetadataManifestTests

We're comparing for unequal manifests but randomBoolean() has a high
probability of getting clashed because of a small search-space, making
test flaky. Let's limit randomization here.

Signed-off-by: Rohit Ashiwal <rashiwal@amazon.com>

server/src/test/java/org/opensearch/gateway/remote/ClusterMetadataManifestTests.java

@@ -90,7 +90,7 @@ public void testClusterMetadataManifestSerializationEqualsHashCode() {
                         builder.nodeId(randomAlphaOfLength(10));
                         break;
                     case 6:
-                        builder.committed(randomBoolean());
+                        builder.committed(!manifest.isCommitted());
                         break;
                     case 7:
                         builder.indices(randomUploadedIndexMetadataList());