PRO-2449 Fixes i18n processing of login throttle message

[abea]

Summary

Resolves PRO-2449. The string was using a pluralization namespace method, but due to the "(s)" part was not taking advantage of pluralization, so it does not need to be using __ns_n().

What are the specific steps to test this change?

1. Pull and install the https://github.com/apostrophecms/apostrophe-boilerplate/tree/temp-pro-2449 branch of apostrophe-boilerplate for A2.
2. Create a user, then attempt to log in three times with an incorrect password. Without this change, you will get a 500 error, shutting down the site. With this change, you see an error message that you'll have to wait 120 minutes.

What kind of change does this PR introduce?

(Check at least one)

• Bug fix
• New feature
• Refactor
• Documentation
• Build-related changes
• Other

Make sure the PR fulfills these requirements:

• It includes a) the existing issue ID being resolved, b) a convincing reason for adding this feature, or c) a clear description of the bug it resolves
• The changelog is updated
• Related documentation has been updated
• Related tests have been updated

If adding a new feature without an already open issue, it's best to open a feature request issue first and wait for approval before working on it.

Other information:

[linear]

PRO-2449 [HelloComputer / Github] apostrophe-login throttle setting produces app crash when used with apostrophe-workflow

https://apostrophecms.atlassian.net/browse/SD-464

Also created by this developer in Github: apostrophecms/apostrophe-workflow#354

[abea]

We're not really using __ns_n anywhere else. looked at the i18n docs for the related method and I don't know if our string here would work. We could change the arguments passed to the original method, though I wasn't clear on that using our wrapper method and there weren't relevant other usages to use as a guide. Ultimately using the simpler method gets this message the same place it woudl have got to before.

[boutell]

This being 2.x, we should do the simplest non-buggy thing that has no significant impact, and this fix appears to be that.