Revert "Disable plural checks for complex messages"

Not related to bug 42631. Simple inspection of the message
content confirms that.

This reverts commit d566e87d2b95840aa28426666fdf8f507b080af5.

Change-Id: I880d4e274568bc2deabff3f192207c0f61e94744
Merge "Revert "Disable plural checks for complex messages""