Refactor contract tests to make it easier to infer contract locations

lib/tasks/contracts/merge_requests.rake

lib/tasks/contracts/pipeline_schedules.rake

lib/tasks/contracts/pipelines.rake

...er/fixtures/project/merge_requests/diffs_batch.fixture.js

...fixtures/project/merge_requests/diffs_metadata.fixture.js

...er/fixtures/project/merge_requests/discussions.fixture.js

...ct/pipeline_schedules/update_pipeline_schedule.fixture.js

...xtures/project/pipelines/create_a_new_pipeline.fixture.js

...mer/fixtures/project/pipelines/delete_pipeline.fixture.js

...s/project/pipelines/get_list_project_pipelines.fixture.js

...res/project/pipelines/get_pipeline_header_data.fixture.js

...tracts/consumer/specs/project/merge_requests/show.spec.js

...ts/consumer/specs/project/pipeline_schedules/edit.spec.js

.../contracts/consumer/specs/project/pipelines/index.spec.js

spec/contracts/consumer/specs/project/pipelines/new.spec.js

spec/contracts/consumer/specs/project/pipelines/show.spec.js

...rge_requests/show/mergerequests#show-get_diffs_batch.json

..._requests/show/mergerequests#show-get_diffs_metadata.json

...rge_requests/show/mergerequests#show-get_discussions.json

.../pipelineschedules#edit-put_edit_a_pipeline_schedule.json