Downgrade the servity of didn't find defined parameter in path to 2 (Azure#26639)

Author: wyunchi-ms

tools/StaticAnalysis/UXMetadataAnalyzer/UXMetadataAnalyzer.cs

@@ -255,7 +255,7 @@ private void ValidateParametersDefinedInPathContainsInExample(IssueLoggerContext
                 if (!isParameterContainsInExample)
                 {
                     string description = string.Format("{0} is defined in path but cannot find in example", parameterFromHttpPath);
-                    issueLogger.LogUXMetadataIssue(context, 1, description);
+                    issueLogger.LogUXMetadataIssue(context, 2, description);
                 }
             }
         }