Remove reference to is_flask_request()

[jonathansberry]

Description

is_flask_request() is deprecated as of CKAN 2.10. All requests are now flask. Here we remove the refernce from a piece of code that was copied from a CKAN core helper when running an older version of CKAN core. This should remove a never ending barage of warnings from production logs.

Checklist

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• The Jira ticket for this issue has been updated to "Ready to Review" or equivalent.
• I have developed these changes in discussion with the appropriate project manager.
• My code follows the general Fjelltopp documentation (see Confluence).
• I have made corresponding changes to the Fjelltopp documentation (see Confluence).
• I have rebased this branch with master.
• New dependency changes have been committed.
• I have added automated tests that prove my fix is effective or that my feature works.
• New and existing tests pass locally with my changes.
• My changes generate no new warnings.
• I have performed a self-review of my own code.
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• I have assigned at least one label to this PR: "patch", "minor", "major".