Print the logs when TPU tests fail (#15533)

(cherry picked from commit 7a8cf4e)

.github/workflows/tpu-tests.yml

@@ -101,10 +101,15 @@ jobs:
         done
         echo "Done waiting. Job status code: $status_code"
         kubectl logs -f $pod_name --container=train > /tmp/full_output.txt
-        grep '<?xml version="1.0" ?>' /tmp/full_output.txt  # sanity check
-        csplit /tmp/full_output.txt '/<?xml version="1.0" ?>/'
-        cat xx00  # test logs
-        mv xx01 coverage.xml
+        if grep -q '<?xml version="1.0" ?>' /tmp/full_output.txt; then
+          # successful run. split the output into logs + coverage report
+          csplit /tmp/full_output.txt '/<?xml version="1.0" ?>/';
+          cat xx00  # test logs
+          mv xx01 coverage.xml
+        else
+          # failed run, print everything
+          cat /tmp/full_output.txt;
+        fi
         exit $status_code
       shell: bash