The logic for the cache in `JwtRealm` produces a broken `Cache` instance to some degree. 
We create a `BytesArray` from the user credential hash:

```java
            final BytesArray jwtCacheKey = isCacheEnabled() ? new BytesArray(jwtAuthenticationToken.getUserCredentialsHash()) : null;
            if (jwtCacheKey != null) {
                final User cachedUser = tryAuthenticateWithCache(tokenPrincipal, jwtCacheKey);
```

and use it as as a cache key in a `Cache` instance down the line.
But then we also clear the bytes in that `BytesArray` to `0` in org.elasticsearch.xpack.security.authc.jwt.JwtAuthenticationToken#clearCredentials. 

This leads to the hash map in the `Cache` getting filled with loads of `BytesArray` that all have the same 0-filled content but that were not equal to each other when first inserted into the map, causing the map to put them all in the same bucket.

<img width="1233" alt="image" src="https://github.com/elastic/elasticsearch/assets/6490959/86a914d7-a2d4-4b01-ad99-e0d14e71a58b">

ref path to the broken map:

<img width="1436" alt="image" src="https://github.com/elastic/elasticsearch/assets/6490959/87ac6f78-bc09-41c4-9a79-28fbbd14f6e6">

x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/authc/jwt/JwtRealm.java
}
    @Override
    public void lookupUser(final String username, final ActionListener<User> listener) {
        ensureInitialized();
        listener.onResponse(null); 
    }
    @Override
    public void expire(final String username) {
        ensureInitialized();
        if (isCacheEnabled()) {
            logger.trace("Expiring JWT cache entries for realm [{}] principal=[{}]", name(), username);
            jwtCacheHelper.removeValuesIf(expiringUser -> expiringUser.user.principal().equals(username));
            logger.trace("Expired JWT cache entries for realm [{}] principal=[{}]", name(), username);
        }
    }
    @Override
    public void expireAll() {
        ensureInitialized();
        invalidateJwtCache();
    }
    @Override
    public AuthenticationToken token(final ThreadContext threadContext) {
        ensureInitialized();
        final SecureString userCredentials = JwtUtil.getHeaderValue(
            threadContext,
            JwtRealm.HEADER_END_USER_AUTHENTICATION,
            JwtRealm.HEADER_END_USER_AUTHENTICATION_SCHEME,
            false
        );
        if (userCredentials == null || userCredentials.isEmpty()) {