make "identifier" attribute true by default in versioned file

Now that I can run tests through to the digitization step thanks to earlier errors being resolved, I now find that digitization unfortunately crashes for our reference Run4 geometry tag...

I believe this is due to handling of the GeoIdentifierTag added in !128 (merged), and so I am hopeful that changing the default value for the associated attribute in the versioned .dtd file will solve this issue similar to the named attribute in !150 (merged)

Adding for comment @dellacqu @mbandier @rbianchi @tsulaia

and for information @tadej @npetters @jmasik @sroe

Any objections to merging this @boudreau? It only touches the versioned file I introduced in a previous MR.

merged

mentioned in commit 7e18fae9

mentioned in merge request atlas/athena!56574 (merged)

For information: after picking up the head of GeoModel the athena MR CI pipelines now succeed! This should mean that we should be good to go ahead with updating once the new tag is made.