Run pipelines of test projects

Adds a job to be extended in analyzers for multi pipeline support

gemnasium-python!28 shows how to leverage this new CI config:

• successful pipeline: https://gitlab.com/gitlab-org/security-products/analyzers/gemnasium-python/pipelines/83002410
• failed pipeline: https://gitlab.com/gitlab-org/security-products/analyzers/gemnasium-python/pipelines/82996180

For SAST:

• gitlab-org/security-products/analyzers/eslint!8 (closed)
• https://gitlab.com/gitlab-org/security-products/tests/js/pipelines/83880276

Non-regression test: https://gitlab.com/gitlab-org/security-products/analyzers/gemnasium-python/pipelines/83821485

gitlab-org/gitlab#10658 (closed)