Palo Alto config source to capture XML configuration improved.

Hello,

We've noticed that the config source 'PaloAlto_FW_RunningConfigXML' that's published on LM repo (version 1.4) doesn't use the best logic to try both API variations.
They're using an IF statement to capture errors after the 1st API attempt, however, the script raises an exception if it fails, which will cause the script to abort & never actually try the 2nd variation.

Instead of an IF statement, this should be done with the try{}catch{} statement, this way it will attempt the 2nd variation if the 1st one fails.
We've published our version on the exchange (code: 9A779T). If it's unavailable there for some reason, you can grab it here.

Thank you!