Bump otel to 1.43.0 and contrib to 0.68.0

See
https://github.com/open-telemetry/opentelemetry-go/releases/tag/v1.41.0
https://github.com/open-telemetry/opentelemetry-go/releases/tag/v1.42.0
https://github.com/open-telemetry/opentelemetry-go/releases/tag/v1.43.0
and
https://github.com/open-telemetry/opentelemetry-go-contrib/releases/tag/v1.41.0
https://github.com/open-telemetry/opentelemetry-go-contrib/releases/tag/v1.42.0
https://github.com/open-telemetry/opentelemetry-go-contrib/releases/tag/v1.43.0
for details.

otelgrpc no longer produces "messages" span events so these are
removed from the tracing test.

Signed-off-by: Stephen Kitt <skitt@redhat.com>

Kubernetes-commit: 1a63916abee48d6356fbc2e6965433647e6cf073