Only add the AIDL manifest decl when using unfrozen

The next release config is always Release_aidl_use_unfrozen=false and
every other config is true.
On the next release config we use prebuilt mainline modules from Android
U, so the Android U swcodec will not serve AIDL.
This becomes a problem when we freeze AIDL interfaces in HAL API freeze
because VTS will start expecting the AIDL service to be registered when
it's declared like this by `mediaserver` even though the `swcodec` is
old and doesn't have AIDL.

Test: launch_cvd
Bug: 279809333
Change-Id: Iacd0f9c800a1c2b7bc932596a0afcc2f5ba7e1aa