Fix NPE when traces collection is disabled

[drodriguezhdez]

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What does this PR do?

This PR prevents the invocation to the DatadogTraceBuildLogic and DatadogTracePipelineLogic instances when the APM trace collection is disabled.

This bug does not affect to any user in the v2.1.0 version cause the form data configuration save action does not create the default configuration for the traces. Related to #114

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