Add skipped state to duration cell

What does this MR do?

Adds a skipped state to duration cell for pipelines.

This is displayed when a pipeline has one stage with a manual job. The wording is off in this use case because a pipeline duration isn't in progress, it hasn't been run yet (since it needs a manual action).

Related to: #324425 (closed)

Screenshots (strongly suggested)

before	after

Multiple stages

Here is a use case with multiple stages. Where skipped shouldn't be shown as well.

Does this MR meet the acceptance criteria?

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