fix: task root in parentRunFacet is not always the same as in dag run #58407
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When working on #57809 I missed support for one case. When only parent information is present in DagRun conf, it's used in DagRun parent run facet as parent and root. Currently, it's not propagated to task root - so in that case task's root is always DagRun, as before.
This PR fixes that, now the root in DagRun's parentRunFacet should always be the same as root in Task's parentRunFacet.
This is the test case that checks that specific scenario:

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