An incomplete shard snapshot will prevent a shard from moving away from a node (see `SnapshotInProgressAllocationDecider`). That means that when a shard snapshot completes it may become possible to perform some shard movements that previously were not possible, so we should trigger a reroute to start those movements. AFAICT we do not trigger such a reroute today.
test/framework/src/main/java/org/elasticsearch/test/ESTestCase.java
Loggers.addAppender(leakLogger, leakAppender);
            
            Runtime.getRuntime().addShutdownHook(new Thread(() -> {
                leakAppender.stop();
                LoggerContext context = (LoggerContext) LogManager.getContext(false);
                Configurator.shutdown(context);
            }));
        }
        BootstrapForTesting.ensureInitialized();
        /*
         * We need to exclude time zones not supported by joda (like SystemV* timezones)
         * because they cannot be converted back to DateTimeZone which we currently
         * still need to do internally e.g. in bwc serialization and in the extract() method
         * //TODO remove once tests do not send time zone ids back to versions of ES using Joda
         */
        Set<String> unsupportedJodaTZIds = Set.of(
            "ACT",
            "AET",
            "AGT",
            "ART",
            "AST",
            "BET",
            "BST",
            "CAT",
            "CNT",
            "CST",
            "CTT",
            "EAT",
            "ECT",
            "EST",