chore: Ignore clirr errors for 7012

Ignore clirr differences for '7012: Method Added to Interface'
for any changes in com.google.logging.v2.ConfigServiceV2Grpc
auto-generated class and its nested interfaces.

Author: minherz

grpc-google-cloud-logging-v2/clirr-ignored-differences.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<differences>
+  <difference>
+    <differenceType>7012</differenceType>
+    <className>com/google/logging/v2/ConfigServiceV2Grpc</className>
+  </difference>
+</differences>