test/kokoro: Add psm-csm build config (#7263)

diff --git a/test/kokoro/psm-csm.cfg b/test/kokoro/psm-csm.cfg
new file mode 100644
index 0000000..25174cd
--- /dev/null
+++ b/test/kokoro/psm-csm.cfg
@@ -0,0 +1,17 @@
+# Config file for internal CI
+
+# Location of the continuous shell script in repository.
+build_file: "grpc-go/test/kokoro/psm-interop-test-go.sh"
+timeout_mins: 120
+
+action {
+  define_artifacts {
+    regex: "artifacts/**/*sponge_log.xml"
+    regex: "artifacts/**/*.log"
+    strip_prefix: "artifacts"
+  }
+}
+env_vars {
+  key: "PSM_TEST_SUITE"
+  value: "csm"
+}