ci: Fix rails spec job run outside of an MR
Currently the rails-specs
jobs rely on the CI_MERGE_REQUEST_IID
and CI_MERGE_REQUEST_SOURCE_BRANCH_SHA
variables to execute. However, if a pipeline is run outside of the context of an MR then these variables are undefined and the jobs will fail.
To resolve this, rely on the pipeline iid to uniquely identify the branch.
Edited by Will Chandler (ex-GitLab)