.gitlab-ci.yml: swap order of extends entries

Previous patch shows that the CI_ONIRO_MAGIC variable, when seen from
the linux-qemu-x86 job, has the value
".oniro-ci/build-generic.yaml:96:.bitbake-workspace". This implies that
the rule-specific variable defined in .gitlab-ci.yml, the
.workspace-rules job, was ignored.

Swap the order of entries in the extends declaration, to see if this has
any effect.

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@huawei.com>