Remove api_dir property

The api_dir property is removed, and the api dir path for aidl_interface
is fixed to aidl_api/{module_name}. According to this rule, all api dirs
are moved to aidl_api/{module_name}.

Bug: 113134692
Test: m -j
Change-Id: I8fcf44928bead86f39e99b17cefec7e351a537a1
Merged-In: I8fcf44928bead86f39e99b17cefec7e351a537a1
(cherry picked from commit ed030373e5a4ab82e6605c69355cf97a7f4c561f)
12 files changed