Don't getContent in OutputPageBodyAttributes handler

EntityId is available as an OutputPage property, passed
via ParserOutput, as a js config variable.

We should be using what is available in parser output /
output page instead of fetching content which is time
and memory intensive.

Bug: 72158
Change-Id: If811e782e796800d36e8199013b813eb9b101937
Merge "Don't getContent in OutputPageBodyAttributes handler"