[scenic] Adjust benchmarks to use STENCIL_SHADOW_VOLUME.

Several shadow techniques previously supported by PaperRenderer "1"
are no longer supported now that PaperRenderer2 is the only option.

TESTABILITY:
The following tests now pass:
( 111 ms )fuchsia.scenic.image_grid_cpp_noclipping_noshadows
( 24 ms )fuchsia.scenic.image_grid_cpp_noclipping_noshadows.catapult_json
( 113 ms )fuchsia.scenic.image_grid_cpp_noshadows
( 24 ms )fuchsia.scenic.image_grid_cpp_noshadows.catapult_json
( 80 ms )fuchsia.scenic.image_grid_cpp_stencil_shadow_volume
( 24 ms )fuchsia.scenic.image_grid_cpp_stencil_shadow_volume.catapult_json
( 50 ms )fuchsia.scenic.image_grid_cpp_x3_noclipping_noshadows
( 29 ms )fuchsia.scenic.image_grid_cpp_x3_noclipping_noshadows.catapult_json
( 39 ms )fuchsia.scenic.image_grid_cpp_x3_noshadows
( 20 ms )fuchsia.scenic.image_grid_cpp_x3_noshadows.catapult_json
( 31 ms )fuchsia.scenic.image_grid_cpp_x3_stencil_shadow_volume
( 18 ms )fuchsia.scenic.image_grid_cpp_x3_stencil_shadow_volume.catapult_json

SCN-1381 #comment

Change-Id: I529bdf69f6fb6870c4ea6e889e7e0630ca9c6d59