[Test] Account for auto-repairing for shard gen file (elastic#112778)

Since elastic#112337, missing shard gen files are automatically reconstructed
based on the existing shard snapshot files. If the list of shard
snapshot files is complete, it means the repository is effectively not
corrupted. This PR updates the test to account for this situation.

Resolves: elastic#112769
(cherry picked from commit e1f7814)

# Conflicts:
#	muted-tests.yml

x-pack/plugin/snapshot-repo-test-kit/src/internalClusterTest/java/org/elasticsearch/repositories/blobstore/testkit/integrity/RepositoryVerifyIntegrityIT.java

@@ -344,16 +344,23 @@ public void testCorruption() throws IOException {
                 ? equalTo(testContext.indexNames().size())
                 : lessThan(testContext.indexNames().size())
         );
-        assertThat(anomalies, not(empty()));
+        // Missing shard generation file is automatically repaired based on the shard snapshot files.
+        // See also BlobStoreRepository#buildBlobStoreIndexShardSnapshots
+        final boolean deletedShardGen = corruptedFileType == RepositoryFileType.SHARD_GENERATION && Files.exists(corruptedFile) == false;
+        assertThat(anomalies, deletedShardGen ? empty() : not(empty()));
         assertThat(responseObjectPath.evaluate("results.total_anomalies"), greaterThanOrEqualTo(anomalies.size()));
-        assertEquals("fail", responseObjectPath.evaluate("results.result"));
+        assertEquals(deletedShardGen ? "pass" : "fail", responseObjectPath.evaluate("results.result"));
 
         // remove permitted/expected anomalies to verify that no unexpected ones were seen
         switch (corruptedFileType) {
             case SNAPSHOT_INFO -> anomalies.remove("failed to load snapshot info");
             case GLOBAL_METADATA -> anomalies.remove("failed to load global metadata");
             case INDEX_METADATA -> anomalies.remove("failed to load index metadata");
-            case SHARD_GENERATION -> anomalies.remove("failed to load shard generation");
+            case SHARD_GENERATION -> {
+                if (deletedShardGen == false) {
+                    anomalies.remove("failed to load shard generation");
+                }
+            }
             case SHARD_SNAPSHOT_INFO -> anomalies.remove("failed to load shard snapshot");
             case SHARD_DATA -> {
                 anomalies.remove("missing blob");