[4.0] Missing J installation error language string

[infograf768]

Summary of Changes

Adding missing string in case a content language can't be created when installing a language during J installation

Saw this when testing #25258 (comment) on a clean install.

Issue will normally be solved by #27854 but better be safe in case a Content Language can't be created at J installation time.

@richard67

[richard67]

@infograf768 I haven't seen that warning, not translated and not untranslated, and this PR here seems to deal with new installation. Shall we do real test or do code review only? Please provide instructions.

[richard67]

@infograf768 Forget my previous question. Got it. Am just testing.

[richard67]

I have tested this item ✅ successfully on e946049

On a clean current 4.0-dev branch as long as PR #27854 hasn't been merged yet, make a new installation.
At the end of installation, customize installation and install e.g. Persian language.
Result: Notice alert shown.
Without PR notice not translated but showing the language string constant.

With this PR: OK, correct message is shown.

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[infograf768]

This new string is just a precaution. There are many possible reasons why a content language could not be created.

[wilsonge]

Thanks!