[ci] Use bdt CI templates more, even for test-only phases

.gitlab-ci.yml

 include: 'https://gitlab.idiap.ch/bob/bob.devtools/raw/master/bob/devtools/data/gitlab-ci/single-package.yaml'
 
-# Redefines the pipeline order for this package
+# Redefines the pipeline order for this package only
 stages:
   - build
   - browser-tests
@@ -9,7 +9,7 @@ stages:
 
 # Docker host based testing (must be run inside dind or docker-enabled host)
 browser_test:
-  extends: .build_linux_template
+  extends: .test_linux_template
   stage: browser-tests
   image: docker.idiap.ch/beat/ci.env.editor:0.0.1r0
   variables:
@@ -24,10 +24,3 @@ browser_test:
     - export LANG=en_US.UTF-8
     - export LANGUAGE=en_US:en
     - export LC_ALL=en_US.UTF-8
-  script:
-    - curl --silent "${BOOTSTRAP}" --output "bootstrap.py"
-    - python3 bootstrap.py -vv channel base
-    - source ${CONDA_ROOT}/etc/profile.d/conda.sh
-    - conda activate base
-    - conda build --test ${CONDA_ROOT}/conda-bld/linux-64/${CI_PROJECT_NAME}-*.tar.bz2
-    - bdt ci clean -vv