ci: merge test phase with build phase

This should speed up CI a bit.

CI stages are separated with a barrier, i.e. all the jobs from the
previous stage must finish before first job of a next phase starts.

In our current build phase we have the following jobs:
 * build (gcc)
 * build (clang-sanitizers)
 * clang-tidy

The build jobs are kind-of fast (ca. 5 and 10 mins, but not in parallel,
i.e. 15 mins in total) and the clang-tidy job is slow (ca. 27 mins).
After the clang-tidy jobs finishes we move on to the test phase where
the CI has to download dependencies (i.e. the build directory) in order
to run tests (ca. 3 + 5 mins, i.e. 8 minutes). I think we can squeeze
this 8 minute-test-jobs into the build phase where we have to wait
anyway.

Also, we don't have to upload and download the build directory which is
a big plus (and can save some time too).

.gitlab-ci.yml

@@ -2,7 +2,6 @@ image: gitlab.fit.cvut.cz:5000/algorithms-library-toolkit/infrastructure/ci-dock
 stages:
  - build
- - test
  - packaging
  - notify
@@ -42,22 +41,13 @@ stages:
     - mkdir -p build && cd build
     - cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -GNinja ..
     - ninja
+    - ctest . --output-on-failure -j $(nproc)
     - DESTDIR="." ninja install
   artifacts:
     paths:
       - build/
     expire_in: 1 day
-.template:test:
-  <<: *only-default
-  dependencies: []
-  stage: test
-  tags:
-    - altbuilder
-  script:
-    - cd build
-    - ctest . --output-on-failure -j $(grep -c processor /proc/cpuinfo)
-
 .config:builder: &distro_builder
   image: gitlab.fit.cvut.cz:5000/algorithms-library-toolkit/infrastructure/ci-docker-images/alt-builder:latest
@@ -65,10 +55,6 @@ stages:
   <<: *distro_builder
   extends: .template:build
-.test:builder:
-  <<: *distro_builder
-  extends: .template:test
-
 build:builder:gcc:
   extends: .build:builder
@@ -78,16 +64,6 @@ build:builder:clang-sanitizers:
     CXX: clang++
     CXXFLAGS: "-fsanitize=address -fsanitize=undefined -fno-sanitize-recover=all" # -stdlib=libc++
-test:builder:gcc:
-  extends: .test:builder
-  dependencies:
-    - build:builder:gcc
-
-test:builder:clang-sanitizers:
-  extends: .test:builder
-  dependencies:
-    - build:builder:clang-sanitizers
-
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 # doc