mediawiki.action.edit.preview: Remove ref to non-existant 'tooltip-p-lang' message

mediawiki.action.edit.preview: Remove ref to non-existant 'tooltip-p-lang' message

This message does not exist in MediaWiki core. And even if one creates it locally,
it is not used by MediaWiki.

It is used for the p-logo link (not the section). And for individual links in
the toolbox and other portlet sections. But not for the sections themselves,
those only have labels (typically rendered as <h3> or something).

This reference was spamming logs with:
> [resourceloader] MessageBlobStore::fetchMessage failed to find tooltip-p-lang (en)

Change-Id: Ie1420230dc0857c1e38641697098b4adb2b28afb