Update Phrase filter regex to support all shortcodes and test shortcode-tests.md page

The following discussion from gitlab-com/localization/tech-docs-forked-projects/prod/gitlab!301 should be addressed:

• @GitLabDuo started a discussion: (+7 comments)

  The Hugo shortcode syntax is inconsistent with the closing tag on line 19. Should use {{< >}} syntax to match the closing tag.

  {{< walkthrough data="duo-walkthrough" >}}

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@wojciech.froelich , as part of this issue, I suggest we do 2 things please:

1. Update Phrase filter to support this shortcode: {{< walkthrough data="duo-walkthrough" >}}. and all shortcodes from our docs (I think the full list is in shortcode-tests.md
2. Test-translate this page and see how it renders: https://gitlab.com/gitlab-org/technical-writing/docs-gitlab-com/-/blob/main/content/shortcode-tests.md