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
logger.debug(
                "Can not build token principal for realm [{}] since claim [{}] is missing from claimSet [{}]",
                name(),
                subClaim,
                jwtClaimsSet
            );
            return null;
        }
        final String userPrincipal = claimParserPrincipal.getClaimValue(jwtClaimsSet);
        if (false == Strings.hasText(userPrincipal)) {
            logger.debug(
                "Can not build token principal for realm [{}] since no user principal can be extracted with [{}]",
                name(),
                claimParserPrincipal
            );
            return null;
        }
        return String.join(",", new TreeSet<>(audiences)) + "/" + subject + "/" + userPrincipal;
    }
    /**
     * JWTClaimsSet values are only allowed to be String, Boolean, Number, or Collection.
     * Collections are only allowed to contain String, Boolean, or Number.
     * Collections recursion is not allowed.
     * Maps are not allowed.
     * Nulls are not allowed.
     * @param value Claim value object.
     * @return True if the claim value is allowed, otherwise false.
     */
    private static boolean isAllowedTypeForClaim(final Object value) {
        return (value instanceof String