Add multi-vm performance tests to Kokoro
diff --git a/.gitignore b/.gitignore
index 5ccad2e..151bbbd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -56,6 +56,7 @@
 
 # Temporary test reports
 report.xml
+*/sponge_log.xml
 latency_trace.txt
 latency_trace.*.txt