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
private void invalidateJwtCache() {
        if (isCacheEnabled()) {
            try {
                logger.trace("Invalidating JWT cache for realm [{}]", name());
                try (ReleasableLock ignored = jwtCacheHelper.acquireForIterator()) {
                    jwtCache.invalidateAll();
                }
                logger.debug("Invalidated JWT cache for realm [{}]", name());
            } catch (Exception e) {
                
                logger.warn("Exception invalidating JWT cache for realm [" + name() + "]", e);
            }
        }
    }
    private boolean isCacheEnabled() {
        return jwtCache != null && jwtCacheHelper != null;
    }
    /**
     * Format and filter JWT contents as user metadata.
     * @param claimsSet Claims are supported. Claim keys are prefixed by "jwt_claim_".
     * @return Map of formatted and filtered values to be used as user metadata.
     */
    private Map<String, Object> buildUserMetadata(JWTClaimsSet claimsSet) {
        final HashMap<String, Object> metadata = new HashMap<>();
        metadata.put("jwt_token_type", jwtAuthenticator.getTokenType().value());
        if (populateUserMetadata) {
            claimsSet.getClaims()
                .entrySet()
                .stream()
                .filter(entry -> isAllowedTypeForClaim(entry.getValue()))