Add a release note about invalid query responses

In recent days, it's been identified that a problem with prepared statements (see MB-22273) can lead to incorrect results being returned by cbq-engine. There are two known workarounds.

1. Do not use prepared statements,
2. If using the Java SDK, use an un-documented property that avoids sending an encoded plan

Note the property is undocumented because it was used for testing/optimization in certain circumstances. It wasn't intended to be in the public API.

Given the severity of this issue, I'd recommend release noting it.