Fix three i18n strings broken by stray pipe characters

What does this MR do and why?

This fixes three strings where a stray pipe causes a problem.

A namespace should be a PascalCase prefix followed by a single pipe, like ApprovalRule|day(s): https://docs.gitlab.com/development/i18n/externalization/#namespaces

Three strings have a problem:

• ee/app/assets/javascripts/ci/pipelines_page/tokens/constants.js: s__('Pipeline|Source|Security Policy')

  !70182 (merged) renamed this family of strings from Pipeline|Source| to PipelineSource|, and this one entry was missed. All 14 sibling entries already use PipelineSource|.

• ee/app/assets/javascripts/security_orchestration/components/policy_editor/scan_result/rule/scan_filters/constants.js: s__('ApprovalRule||year(s)').

  This had a doubled pipe. The three sibling entries above it use a single pipe.

• app/assets/javascripts/analytics/shared/components/value_streams_dashboard_link.vue: __('Value Streams Dashboard | DORA')

  Here the pipe is part of the visible label, not a namespace. Translators read it as a namespace anyway and translated only what followed it. All ten locales that have a translation return just "DORA", for example in locale/ja/gitlab.po:

  msgid "Value Streams Dashboard | DORA"
  msgstr "DORA"

  Now Value Streams Dashboard (DORA). The @gitlab/require-valid-i18n-helpers ESLint rule already flagged this and had been disabled in place. That disable comment is removed. Related to VSA - adding drill-up link to VSD comparison page (!112787 - merged)

For the first two there is no visible change in the UI. The pgettext helper in app/assets/javascripts/locale/index.js splits the key on the pipe character and returns the last segment, so both the old and new keys already render as "Security Policy" and "year(s)". The third is different: it is a real bug in those ten languages, where the link reads "DORA" instead of the full label.

The first two still matter because:

• Any code that strips the namespace up to the first pipe (the canonical rule used by msgid_without_namespace in lib/gitlab/i18n/translation_entry.rb) resolves these to the wrong labels: Source|Security Policy and |year(s).
• Crowdin shows the namespace to translators as context, so an empty segment and a two part prefix are both misleading.
• These were found while building a documentation linter that checks UI text in docs against locale/gitlab.pot (!253587 (merged))

References

• Related to Mark UI text with shortcodes and validate it ag... (!253587 - merged)
• Related to Fix multiple strings in translations (|, space,... (!70182 - merged)
• Related to Hugo shortcode to flag UI text instead of relyi... (gitlab-org/technical-writing/docs-gitlab-com#733 - closed)

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This merge request was drafted with Claude Code.