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/JwtRealmAuthenticateTests.java
)
                .put(RealmSettings.getFullSettingKey(realmName, JwtRealmSettings.ALLOWED_AUDIENCES), jwtIssuer.audiencesClaimValue.get(0))
                .put(RealmSettings.getFullSettingKey(realmName, JwtRealmSettings.CLAIMS_PRINCIPAL.getClaim()), jwtIssuer.principalClaimName)
                .put(
                    RealmSettings.getFullSettingKey(realmName, JwtRealmSettings.CLIENT_AUTHENTICATION_TYPE),
                    JwtRealmSettings.ClientAuthenticationType.SHARED_SECRET.value()
                );
            if (jwtIssuer.encodedJwkSetPkcPublic.isEmpty() == false) {
                authcSettings.put(
                    RealmSettings.getFullSettingKey(realmName, JwtRealmSettings.PKC_JWKSET_PATH),
                    saveToTempFile("jwkset.", ".json", jwtIssuer.encodedJwkSetPkcPublic)
                );
            }
            
            final MockSecureSettings secureSettings = new MockSecureSettings();
            if (jwtIssuer.algAndJwksHmac.isEmpty() == false) {
                secureSettings.setString(
                    RealmSettings.getFullSettingKey(realmName, JwtRealmSettings.HMAC_JWKSET),
                    jwtIssuer.encodedJwkSetHmac
                );
            }
            if (jwtIssuer.encodedKeyHmacOidc != null) {
                secureSettings.setString(
                    RealmSettings.getFullSettingKey(realmName, JwtRealmSettings.HMAC_KEY),
                    jwtIssuer.encodedKeyHmacOidc
                );
            }
            secureSettings.setString(
                RealmSettings.getFullSettingKey(realmName, JwtRealmSettings.CLIENT_AUTHENTICATION_SHARED_SECRET),
                clientSecret