Remove redundant sentence in openid-convert-already-your-openid-text

<https://translatewiki.net/wiki/Thread:Support/About_MediaWiki:Openid-convert-already-your-openid-text/ia>

Change-Id: I14b691edef437dea2c05d1047cdba9e01525e6db
Merge "Remove redundant sentence in openid-convert-already-your-openid-text"