Update the Go version and path to the test file.

With have higher number of targets (seen on 600+), no matter in single
probe or in different probes, we may cause network buffer overflow as
we add packets to the buffer much faster than NIC can handle them.
To avoid this we may increase net.core.wmem sysctl, or add 1 microsecond
dalay between buffer writes (which is done by this patch). This allows
to have stable results for even 2k targets in single probe.

Also patch improves logging
 - Added debug log when probe is started.
 - Do not print duplicate p.name as it is always added by logger,
   add p.runCnt instead
 - Improve debug message for a case when packet does not match runId
   this is usually happening when we received packet after probe timeout.

Note: This feature works only for textproto based (original format) configs right now, i.e. YAML doesn't work yet.

Cloudprober configs now support including other config files through an 'include' statement. See example at:
https://github.com/cloudprober/cloudprober/tree/master/examples/include

A few points:
- We do an in place substitution of the included files. This works well as it is for protobuf (textproto) based configs, but not so well for YAML configs.
- Nested includes work as well.

* Also, fix a possible race condition in cloudprober_test.

- Enable add_failure_metric for all surfacers except FILE and PUBSUB.
- Add enable/disable metrics by name functionality to all surfacers
  except FILE and PUBSUB.
- Update documentation to include the OpenTelemetry option.

…#656)

- Container ID is a super long string and is not very useful.
- Pod info is available as host name on k8s.

- Default prefix is cloudprober_.
- This is important to identify cloudprober metrics on the final
metrics system.