Fix minor word duplication

products/monitoring/terraform.yaml

@@ -82,7 +82,7 @@ overrides: !ruby/object:Overrides::ResourceOverrides
           to avoid a diff, Terraform will use the state value if it appears
           that the obfuscated value matches the state value in
           length/unobfuscated characters. However, Terraform will not detect a
-          a diff if the obfuscated portion of the value was changed outside of
+          diff if the obfuscated portion of the value was changed outside of
           Terraform.
         custom_flatten: "templates/terraform/custom_flatten/monitoring_obfuscated_labels.go.erb"