Add RunNumber to Each Workspace in Multi-Period Event Data

[TTitcombe]

Description of work.
Swap the ordering of adding information to logs in LoadEventNexus so that metadata is added before we copy the metadata to each workspace in the collection

Report to: nobody

To test:
In Mantid, load LARMOR13065. (this is in ExternalData/Testing/Data/SystemTest/LARMOR of your build directory)
This should produce a group workspace with 4 constituents.
Right click on each individual workspace and click sample logs.
The logs should contain mostly the same elements, but this PR is specifically to ensure that each workspace has the property run number, and the value should be 13065 in each workspace.

Fixes #24583

This does not require release notes because internal change

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Reviewer

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[LowriJenkins]

changes function as described, and only change in code is moving a section earlier.