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/test/java/org/elasticsearch/xpack/security/authc/jwt/JwtRealmTestCase.java
} else {
                authcSettings.putList(
                    RealmSettings.getFullSettingKey(
                        new RealmConfig.RealmIdentifier(JwtRealmSettings.TYPE, authcRealmName),
                        SSLConfigurationSettings.CAPATH_SETTING_REALM
                    ),
                    JwtIssuerHttpsServer.CERT_PATH.toString()
                );
                jwkSetPath = jwtIssuer.httpsServer.url;
            }
            authcSettings.put(RealmSettings.getFullSettingKey(authcRealmName, JwtRealmSettings.PKC_JWKSET_PATH), jwkSetPath);
        }
        if (randomBoolean()) {
            
            authcSettings.put(RealmSettings.getFullSettingKey(authcRealmName, JwtRealmSettings.CLAIMS_PRINCIPAL.getPattern()), "^(.*)$");
        }
        if (randomBoolean()) {
            
            authcSettings.put(
                RealmSettings.getFullSettingKey(authcRealmName, JwtRealmSettings.CLAIMS_GROUPS.getClaim()),
                authcRealmName + "_groups"
            );
            if (randomBoolean()) {
                
                authcSettings.put(RealmSettings.getFullSettingKey(authcRealmName, JwtRealmSettings.CLAIMS_GROUPS.getPattern()), "^(.*)$");
            }
        }
        if (randomBoolean()) {
            
            authcSettings.put(