Enables tracing in the email and recommendation services, which was disabled in 316db88 because of a memory leak in the stackdriver exporter.
We fixed the leak in https://github.com/googleapis/google-cloud-python/pull/6856. The fix is included in the [0.1.10 release of opencensus-python](https://github.com/census-instrumentation/opencensus-python/releases/tag/v0.1.10).
With this diff, traces show up as expected in stackdriver while running the demo on GKE. Using an `opencensus-python` package version before `0.1.10` causes the email and recommendation services to leak memory until they OOM. Memory use is back to normal (i.e. roughly constant) using the new package version.
change the log format in Python and Node.js services.
Effected services are currencyservice, emailservice, paymentservice,
and recommendationservice. Loadgenerator is left as is because of
the diffculty to change the log format and log target in locust.
ref. #47
enabling the tracing interceptor/sampler causes an unbounded memory leak
eventually OOMing the container.
Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>
