Change "Pipeline|Source|" to "PipelineSource|"

The following strings expect the first string uses double "|". I suggest only using a single "|" as to not confuse translators.

Pipeline|Source
Pipeline|Source|API
Pipeline|Source|Chat
Pipeline|Source|External
Pipeline|Source|External Pull Request
Pipeline|Source|Merge Request
Pipeline|Source|On-Demand DAST Scan
Pipeline|Source|On-Demand DAST Validation
Pipeline|Source|Parent Pipeline
Pipeline|Source|Pipeline
Pipeline|Source|Push
Pipeline|Source|Schedule
Pipeline|Source|Trigger
Pipeline|Source|Web
Pipeline|Source|Web IDE

https://gitlab.com/gitlab-org/gitlab/-/blob/master/app/assets/javascripts/pipelines/components/pipelines_list/tokens/pipeline_source_token.vue#L24-76

There are other strings that uses "PipelineCharts|" so i guess we could use "PipelineSource|" for these strings.