ci: Fix publishing to pages from default branch

ci: Fix publishing to pages from default branch

Commit 728c9142 "Use CI_DEFAULT_BRANCH as the default branch" actually broke the publishing via GitLab pages from the default branch since the only: [ ${CI_DEFAULT_BRANCH} ] condition was not really expanding the variable and it was considering ${CI_DEFAULT_BRANCH} as a literal branch name.

This means that the test-pdf job got always instantiated while pages never was, regardless of the branch they where running on.

By switching to rules: we can properly implement automatic default branch detection and fix the regression.

Signed-off-by: Ritesh Raj Sarraf ritesh.sarraf@collabora.com