Adjust naming in admin network settings

What does this MR do and why?

• Lowercase the "rate limits" part of the section titles in the admin network settings page to be consistent with the rest of the application settings page. e.g. Files API rate limits instead of Files API Rate Limits
• Pluralize the "rate limits" part of the section titles in the admin network settings page, e.g. Users API rate limits instead of Users API rate limit

Changelog: other

🛠 with ❤ at Siemens

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

MR Checklist (@gerardo-navarro)

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the javascript style guides
• Conforms to the database guides

Screenshots or screen recordings

Only frontend UI text changes.

Before	After

How to set up and validate locally

1. Go to http://gdk.test:3000/admin/application_settings/network#js-ip-limits-settings
2. Look at the sections related to rate limits => the section titles should be aligned