(#19760) Fix sun provider

The `sun` provider is not able to install packages anymore because when querying an absent package, the following exception is raised:

    Unable to get information about package SMCcurl because of: No message

This seems to be a regression caused by 41356a7: When a package is absent the `pkginfo` command will print the following warning and exit with a non zero exitcode:

    ERROR: information for "SMCcurl" was not found

The above message is printed on STDERR but the `sun` provider only reads STDOUT to check for known error messages.

Fix the provider and react on Puppet::ExecutionFailure.

Note: This should be merged into a bugfix release