Replace RuleBuilder usages with static rules in app_import.go

RuleBuilder creates a new rule in the ninja file every time
it's used, but in this case the rules were all exactly the same
except that the input/output file paths were different.

This can be converted to a single static rule instead.

Bug: 262629589
Test: m nothing
Change-Id: Iaa887c66a757da13293a3614c000d3be02a2a1b0