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
if (authzRealmNames.isEmpty() == false) {
            final String selected = randomFrom(authzRealmNames);
            for (final String authzRealmName : authzRealmNames) {
                final RealmConfig authzConfig = buildRealmConfig("authz", authzRealmName, Settings.EMPTY, allRealms.size() + 1);
                final MockLookupRealm authzRealm = new MockLookupRealm(authzConfig);
                if (authzRealmName.equals(selected)) {
                    jwtIssuer.principals.values().forEach(authzRealm::registerUser);
                }
                allRealms.add(authzRealm);
            }
        }
        return jwtRealm;
    }
    protected JwtIssuerAndRealm randomJwtIssuerRealmPair() throws ParseException {
        
        assertThat(jwtIssuerAndRealms, notNullValue());
        assertThat(jwtIssuerAndRealms, not(empty()));
        final JwtIssuerAndRealm jwtIssuerAndRealm = randomFrom(jwtIssuerAndRealms);
        final JwtRealm jwtRealm = jwtIssuerAndRealm.realm;
        assertThat(jwtRealm, notNullValue());
        assertThat(JwtRealmInspector.getAllowedIssuer(jwtRealm), equalTo(jwtIssuerAndRealm.issuer.issuerClaimValue));
        assertThat(
            jwtIssuerAndRealm.issuer.audiencesClaimValue.stream().anyMatch(JwtRealmInspector.getAllowedAudiences(jwtRealm)::contains),
            is(true)
        );
        printJwtRealmAndIssuer(jwtIssuerAndRealm);
        return jwtIssuerAndRealm;
    }
    protected void doMultipleAuthcAuthzAndVerifySuccess(