Change the syntax and non-one count fake values for {{PLURAL: in newmessages*

Change the newmessageslinkplural and newmessagesdifflinkplural syntax and non-one count fake values to 999.

Bug: 42497
Change-Id: I2a4b739314e524c3e70184766bb047cf54707c63
Merge "Change the syntax and non-one count fake values for {{PLURAL: in newmessages*"