OBMCEncodeTest: encode fewer frames for two high bitrate tests.

This is to speed-up these slow unit tests.

Note that the purpose of the tests is to ensure OBMC works correctly for
non-multiple-of-64 wide clip. So, encoding fewer frames will still
ensure this coverage.

Also, the lower bitrate test still encodes same number of frames as
before to ensure more coverage.
diff --git a/test/obmc_encode_test.cc b/test/obmc_encode_test.cc
index 5d5a90e..211664a 100644
--- a/test/obmc_encode_test.cc
+++ b/test/obmc_encode_test.cc
@@ -79,7 +79,7 @@
   const unsigned int bit_depth = 8;
 
   ::libaom_test::I420VideoSource video("hantro_odd.yuv", width, height, 30, 1,
-                                       0, 10);
+                                       0, 5);
 
   init_flags_ = AOM_CODEC_USE_PSNR;
 
@@ -130,8 +130,7 @@
   cfg_.rc_max_quantizer = 40;
   cfg_.rc_min_quantizer = 0;
 
-  ::libaom_test::I420VideoSource video("hantro_odd.yuv", 208, 144, 30, 1, 0,
-                                       10);
+  ::libaom_test::I420VideoSource video("hantro_odd.yuv", 208, 144, 30, 1, 0, 5);
 
   ASSERT_NO_FATAL_FAILURE(RunLoop(&video));
 }