On macOS monterey, `java -version` returns
```
The operation couldn’t be completed. Unable to locate a Java Runtime.
Please visit http://www.java.com for information on installing Java.

```
which does not match the existing regex. Instead of hitting a fatal error if required,
reset the variable and let FindPackage handle the result.

If `QUIET` is requested, don't print anything if the version query fails. Otherwise, print the message.

Additionally, clean up temporary variables set by the execute_process commands.