i18n: plural support for securepoll-create-layout-election_dates

- $2 is HTML code and cannot be used for PLURAL

Spotted by Robby
https://translatewiki.net/wiki/Thread:Support/About:MediaWiki:Securepoll-create-layout-election_dates/en

Change-Id: I56ae7f6b2bebef2a10153454aa7188525246a0f5
Merge "i18n: plural support for securepoll-create-layout-election_dates"