testing: reduce sampling on volume tests to make them faster (#2119)

Signed-off-by: Larry Gritz <lg@larrygritz.com>

Author: lgritz

.github/workflows/ci.yml

@@ -326,7 +326,7 @@ jobs:
                             LLVM_VERSION=14.0.0 LLVM_DISTRO_NAME=ubuntu-18.04
                             PUGIXML_VERSION=v1.9
                             CTEST_TEST_TIMEOUT=1800
-                            OSL_CMAKE_FLAGS="-DOSL_TEST_BIG_TIMEOUT=1800"
+                            OSL_CMAKE_FLAGS="-DOSL_TEST_BIG_TIMEOUT=1200"
           - desc: gcc10/C++17 llvm14 oiio-2.5 avx2
             nametag: linux-2021ish-gcc10-llvm14
             runner: ubuntu-22.04

testsuite/render-mx-anisotropic-vdf/ref/out-linux-alt.exr

@@ -6,5 +6,7 @@
 
 failthresh = 0.01
 failpercent = 1
+allowfailures = 5
+
 outputs = [ "out.exr" ]
-command = testrender("-v -r 196 196 -aa 64 scene.xml out.exr")
+command = testrender("-v -r 196 196 -aa 32 scene.xml out.exr")

testsuite/render-mx-anisotropic-vdf/ref/out-macos-alt.exr

@@ -6,5 +6,7 @@
 
 failthresh = 0.01
 failpercent = 1
+allowfailures = 5
+
 outputs = [ "out.exr" ]
-command = testrender("-r 196 196 -aa 32 scene.xml out.exr")
+command = testrender("-r 196 196 -aa 16 scene.xml out.exr")