DAOS-16272 dfs: fix get_info returning incorrect oclass (#15048)

[mchaarawi]

If user creates a container without --file-oclass, the get_info call was returning the default oclass of a directory on daos fs get-attr. Fix that to properly use the enum types for default scenario.

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[github-actions]

Ticket title is 'File Creation oclass for dir attributes showing as S1 for default file-oclass'
Status is 'Open'
Labels: 'request_for_2.6.1,triaged'
https://daosio.atlassian.net/browse/DAOS-16272

[daosbuild1]

Test stage Functional Hardware Large completed with status FAILURE. https://build.hpdd.intel.com//job/daos-stack/job/daos/view/change-requests/job/PR-15058/1/execution/node/1508/log