[REF] [Import] Use shared file instead of now-identical files

[eileenmcnaughton]

Overview

Use shared file instead of now-identical files

Before

#23186 updated the 2 DataSource.tpl files to be identical - but I left them in place to keep the diff readable

After

The guts of the file is now moved to a shared location

I put up screenshots just to show they actually still load.... & that I did an r-run

Technical Details

Comments

@colemanw - I didn't do any extra steps here so should be an easy merge

[civibot]

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[eileenmcnaughton]

@colemanw @seamuslee001 would be great to get a merge on this - I did literally move the file so it is exactly the same...