Fix missing test name after aosp/2372150

The test name defaulting to ctx.ModuleName() was
accidentally removed, readd it

Bug: 184895128
Fixes: 264423240
Fixes: 264433459
Test: Verified ninja files produced with this cl and aosp/2372150 are the same as with aosp/2372150 reverted
Change-Id: I23ab8ab39132b93719cc6f797d92b1cabce5eae9