Exclude _generated files form PoliCheck run (Azure#22854)

Author: chidozieononiwu

eng/guardian-tools/policheck/PolicheckExclusions.xml

@@ -1,7 +1,7 @@
 <PoliCheckExclusions>
 <!-- All strings must be UPPER CASE -->
 <!-- Each of these exclusions is a folder name - if \[name]\ exists in the file path, it will be skipped -->
-<!--<Exclusion Type="FolderPathFull">ABC|XYZ</Exclusion>-->
+<Exclusion Type="FolderPathFull">_GENERATED</Exclusion>
 <!-- Each of these exclusions is a folder name - if any folder or file starts with "\[name]", it will be 
 skipped -->
 <!--<Exclusion Type="FolderPathStart">ABC|XYZ</Exclusion>-->