De/Serialization errors during running integ tests

[crasu]

Describe the Issue

After merging 13728 we are getting de/serialization error messages while running integ tests. The messages do not cause the test to fail but do clutter the tests output.

Your Environment

• Happens on current CI or dev vm
• Example from CI: https://github.com/magma/magma/actions/runs/3264233654/jobs/5364550125#step:10:7324

Screenshots

[libprotobuf ERROR google/protobuf/wire_format_lite.cc:618] String field 'io.prometheus.client.LabelPair.value' contains invalid UTF-8 data when parsing a protocol buffer. Use the 'bytes' type if you intend to send raw bytes.