Current default directory requires android:requestLegacyExternalStorage on Q+ devices. See b/145598917#comment7 for this hitting us in CI (not the first time).

Changing the default is difficult, since it's hard coded in older versions of AGP. We could change it, and give people an option to change it back via inst arg, e.g. androidx.benchmark.legacyOutputDirectory=true

The simpler approach would be to set android:requestLegacyExternalStorage=true in our manifest, and avoid the complexity for clients, at the cost of setting a legacy behavior flag without app involvement. As our library is only expected to be used for testing purposes, this may be fine.