Use main build.sh to build docs in docs CI (#3681)

Authors:
  - Dante Gama Dessavre (https://github.com/dantegd)

Approvers:
  - Ray Douglass (https://github.com/raydouglass)
  - Dillon Cullinan (https://github.com/dillon-cullinan)

URL: #3681

ci/docs/build.sh

@@ -46,9 +46,8 @@ conda list --show-channel-urls
 
 # Build Doxygen docs
 gpuci_logger "Build Doxygen docs"
-cd $PROJECT_WORKSPACE/cpp/build
-make doc
-
+$PROJECT_WORKSPACE/build.sh cppdocs -v
+
 # Build Python docs
 gpuci_logger "Build Sphinx docs"
 cd $PROJECT_WORKSPACE/docs