setLocale: precaution for when setLocale is called on an unilingual site

[mlutfy]

Overview

This is a small tweak for a specific use-case:

• CiviCRM is running in a single language (i.e. not multi-lingual)
• The site is using an extension that uses CRM_Core_I18n::setLocale(), but not checking if the site is in multi-lingual (ex: cdntaxreceipts).

but it might also cover the use-case where a site uses the multi-gettext language option, but not multi-lingual database (ex: #13240).

Before

Calling setLocale() on a non-multilingual DB would cause subsequent SQL queries to fail, because the dbLocale suffix gets set, but the sql views do not exist.

After

DB queries do not fail.

[civibot]

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[seamuslee001]

This looks sane to me adding merge on pass as we have enough multilingual tests to confirm if this is fine or not

[eileenmcnaughton]

@mlutfy is this addressing a potential recent regression? If so it should be against the rc

[mlutfy]

@eileenmcnaughton No it's been like that for a while.