Propagate trace/span IDs via environment variables for Jenkins Pipelines

[drodriguezhdez]

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What does this PR do?

In this PR we propagate the trace/span IDs as environment variables to be able to continue the trace using datadog-ci CLI.
Environment variables:

• DD_CUSTOM_TRACE_ID
• DD_CUSTOM_PARENT_ID

Description of the Change

Alternate Designs

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