Fix SnapshotRetentionConfigurationTests (#101603) (#101662)

The test failure happens as we choose same ids with `"snap-" +
randomAlphaOfLength(3)`. This change uses UUID for ids to minimize the change of
 collisions.

Author: idegtiarenko

server/src/main/java/org/elasticsearch/repositories/RepositoryData.java

@@ -1214,6 +1214,22 @@ public int hashCode() {
             return Objects.hash(snapshotState, version, startTimeMillis, endTimeMillis, slmPolicy);
         }
 
+        @Override
+        public String toString() {
+            return "SnapshotDetails{"
+                + "snapshotState="
+                + snapshotState
+                + ", version="
+                + version
+                + ", startTimeMillis="
+                + startTimeMillis
+                + ", endTimeMillis="
+                + endTimeMillis
+                + ", slmPolicy='"
+                + slmPolicy
+                + "'}";
+        }
+
         public static SnapshotDetails fromSnapshotInfo(SnapshotInfo snapshotInfo) {
             return new SnapshotDetails(
                 snapshotInfo.state(),

test/framework/src/main/java/org/elasticsearch/test/ESTestCase.java

@@ -43,6 +43,7 @@
 import org.elasticsearch.client.internal.Requests;
 import org.elasticsearch.cluster.ClusterModule;
 import org.elasticsearch.cluster.metadata.IndexMetadata;
+import org.elasticsearch.common.UUIDs;
 import org.elasticsearch.common.bytes.BytesArray;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.bytes.CompositeBytesReference;
@@ -996,6 +997,10 @@ public static String randomIdentifier() {
         return randomAlphaOfLengthBetween(8, 12).toLowerCase(Locale.ROOT);
     }
 
+    public static String randomUUID() {
+        return UUIDs.randomBase64UUID(random());
+    }
+
     public static String randomUnicodeOfLengthBetween(int minCodeUnits, int maxCodeUnits) {
         return RandomizedTest.randomUnicodeOfLengthBetween(minCodeUnits, maxCodeUnits);
     }

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/slm/SnapshotRetentionConfigurationTests.java

@@ -313,7 +313,7 @@ private SnapshotInfo makeInfo(long startTime) {
         meta.put(SnapshotsService.POLICY_ID_METADATA_FIELD, REPO);
         final int totalShards = between(1, 20);
         SnapshotInfo snapInfo = new SnapshotInfo(
-            new Snapshot(REPO, new SnapshotId("snap-" + randomAlphaOfLength(3), "uuid")),
+            new Snapshot(REPO, new SnapshotId("snap-" + randomUUID(), "uuid")),
             Collections.singletonList("foo"),
             Collections.singletonList("bar"),
             Collections.emptyList(),