Tracing and Platform fixes

[tiagolobocastro]

feat(platform): support custom namespace

When we run outside of the cluster, we can't just use the env to determine
the correct namespace..
For now we expose an additional method which allows overriding it.
A better solution is perhaps to simply ensure we create clients with the
correct namespace as default?

Signed-off-by: Tiago Castro <tiagolobocastro@gmail.com>

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fix(agents/core): use tracing api

Incorrect log api was used for error logging.
Also include error source in the service error.

Signed-off-by: Tiago Castro <tiagolobocastro@gmail.com>

[tiagolobocastro]

bors merge

[bors-openebs-mayastor]

Build succeeded:

• continuous-integration/jenkins/branch