Parse page content using the standard parser first for link tables

We could do this using TextContent::fillParserOutput(), but alas it is
'protected', so we have to duplicate a tiny bit of code from there.

Bug: 68757
Change-Id: I7d98fa0f97fb195d23caa3d7448a15c3bbe430ca
Merge "Parse page content using the standard parser first for link tables"