[`Setting.versionSetting`](https://github.com/elastic/elasticsearch/blob/0652a5915586abbcdfdfffa91a391740f0147752/server/src/main/java/org/elasticsearch/common/settings/Setting.java#L1275) (only used by index compatibility setting) does not use the `Validator` passed in - its just discarded. Looks like it's been like this since it was introduced by https://github.com/elastic/elasticsearch/pull/83264 in 8.2.0.

Enabling this causes some tests to fail. Enabling this may cause problems for indexes that have a wonky setting already applied.
server/src/main/java/org/elasticsearch/common/settings/Setting.java
import org.elasticsearch.common.regex.Regex;
import org.elasticsearch.common.unit.ByteSizeValue;
import org.elasticsearch.common.unit.MemorySizeValue;
import org.elasticsearch.common.xcontent.XContentParserUtils;
import org.elasticsearch.core.Booleans;
import org.elasticsearch.core.Nullable;
import org.elasticsearch.core.TimeValue;
import org.elasticsearch.core.Tuple;
import org.elasticsearch.index.mapper.DateFieldMapper;
import org.elasticsearch.xcontent.ToXContentObject;
import org.elasticsearch.xcontent.XContentBuilder;
import org.elasticsearch.xcontent.XContentFactory;
import org.elasticsearch.xcontent.XContentParser;
import org.elasticsearch.xcontent.XContentParserConfiguration;
import org.elasticsearch.xcontent.XContentType;
import java.io.IOException;
import java.time.Instant;
import java.util.Arrays;
import java.util.Collections;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;