Fix sentence structure mentioning cooldown period (#8197)

The text should be two sentences, or at the very least separated by a semicolon rather than a comma.

## Checklist

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### Tests

- I added test coverage for Go changes...
  - [ ] in their respective `*_test.go` for unit tests.
  - [x] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I added test coverage for JavaScript changes...
  - [ ] in `web_src/js/*.test.js` if it can be unit tested.
  - [ ] in `tests/e2e/*.test.e2e.js` if it requires interactions with a live Forgejo server (see also the [developer guide for JavaScript testing](https://codeberg.org/forgejo/forgejo/src/branch/forgejo/tests/e2e/README.md#end-to-end-tests)).

### Documentation

- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [x] I do not want this change to show in the release notes.
- [ ] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8197
Reviewed-by: 0ko <0ko@noreply.codeberg.org>
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: John Veness <john-codeberg@jveness.co.uk>
Co-committed-by: John Veness <john-codeberg@jveness.co.uk>

options/locale/locale_en-US.ini

@@ -768,8 +768,8 @@ update_profile_success = Your profile has been updated.
 change_username = Your username has been changed.
 change_username_prompt = Note: Changing your username also changes your account URL.
 change_username_redirect_prompt = The old username will redirect until someone claims it.
-change_username_redirect_prompt.with_cooldown.one = The old username will be available to everyone after a cooldown period of %[1]d day, you can still reclaim the old username during the cooldown period.
-change_username_redirect_prompt.with_cooldown.few = The old username will be available to everyone after a cooldown period of %[1]d days, you can still reclaim the old username during the cooldown period.
+change_username_redirect_prompt.with_cooldown.one = The old username will be available to everyone after a cooldown period of %[1]d day. You can still reclaim the old username during the cooldown period.
+change_username_redirect_prompt.with_cooldown.few = The old username will be available to everyone after a cooldown period of %[1]d days. You can still reclaim the old username during the cooldown period.
 continue = Continue
 cancel = Cancel
 language = Language
@@ -2931,8 +2931,8 @@ settings.update_settings = Update settings
 settings.update_setting_success = Organization settings have been updated.
 settings.change_orgname_prompt = Note: Changing the organization name will also change your organization's URL and free the old name.
 settings.change_orgname_redirect_prompt = The old name will redirect until it is claimed.
-settings.change_orgname_redirect_prompt.with_cooldown.one = The old organization name will be available to everyone after a cooldown period of %[1]d day, you can still reclaim the old name during the cooldown period.
-settings.change_orgname_redirect_prompt.with_cooldown.few = The old organization name will be available to everyone after a cooldown period of %[1]d days, you can still reclaim the old name during the cooldown period.
+settings.change_orgname_redirect_prompt.with_cooldown.one = The old organization name will be available to everyone after a cooldown period of %[1]d day. You can still reclaim the old name during the cooldown period.
+settings.change_orgname_redirect_prompt.with_cooldown.few = The old organization name will be available to everyone after a cooldown period of %[1]d days. You can still reclaim the old name during the cooldown period.
 settings.update_avatar_success = The organization's avatar has been updated.
 settings.delete = Delete organization
 settings.delete_account = Delete this organization

tests/integration/user_redirect_test.go

@@ -143,7 +143,7 @@ func TestUserRedirect(t *testing.T) {
 			defer test.MockVariableValue(&setting.Service.UsernameCooldownPeriod, 8)()
 			defer tests.PrintCurrentTest(t)()
 
-			assert.Contains(t, getPrompt(t), "The old username will be available to everyone after a cooldown period of 8 days, you can still reclaim the old username during the cooldown period.")
+			assert.Contains(t, getPrompt(t), "The old username will be available to everyone after a cooldown period of 8 days. You can still reclaim the old username during the cooldown period.")
 		})
 	})
 
@@ -167,7 +167,7 @@ func TestUserRedirect(t *testing.T) {
 			defer test.MockVariableValue(&setting.Service.UsernameCooldownPeriod, 8)()
 			defer tests.PrintCurrentTest(t)()
 
-			assert.Contains(t, getPrompt(t), "The old organization name will be available to everyone after a cooldown period of 8 days, you can still reclaim the old name during the cooldown period.")
+			assert.Contains(t, getPrompt(t), "The old organization name will be available to everyone after a cooldown period of 8 days. You can still reclaim the old name during the cooldown period.")
 		})
 	})
 }