ci: Parallelize integration tests

Run integration tests for library and executables in parallel (the
signstaros related tests are still run separately).

Signed-off-by: David Runge <dvzrv@archlinux.org>

.gitlab-ci.yml

@@ -4,8 +4,7 @@ variables:
 stages:
   - check
   - test
-  - library-integration
-  - executables
+  - integration
   - signstaros
   - publish
   - report
@@ -65,7 +64,7 @@ integration-test:
     - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
   script:
     - WORKDIR="$(pwd)" runuser -w WORKDIR -l testuser -c 'env && cd "$WORKDIR" && just install-rust-dev-tools && just ignored=true test'
-  stage: library-integration
+  stage: integration
   tags:
     - vm
 
@@ -81,7 +80,7 @@ test-readmes:
     - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
   script:
     - WORKDIR="$(pwd)" runuser -w WORKDIR -l testuser -c 'env && cd "$WORKDIR" && just install-rust-dev-tools && just test-readmes'
-  stage: executables
+  stage: integration
   tags:
     - vm