Remove vale alert box rules

We have changed how we use alert boxes in the docs,
and these rules no longer match the style.

doc/.vale/gitlab/AlertBoxCaution.yml

----
-# Error: gitlab.AlertBoxCaution
-#
-# Makes sure CAUTION: alert boxes follow standard formatting.
-#
-# For a list of all options, see https://errata-ai.gitbook.io/vale/getting-started/styles
-extends: substitution
-message: "CAUTION: alert boxes must be of the format 'CAUTION: **Caution:**'. 'Caution' can be replaced with 'Warning' or 'Important'."
-link: https://docs.gitlab.com/ee/development/documentation/styleguide.html#alert-boxes
-level: warning
-nonword: true
-scope: raw
-swap:
-  'CAUTION: *?\*\*.*\*\*': 'CAUTION: \*\*(?:Caution|Warning|Important):\*\*'

doc/.vale/gitlab/AlertBoxDanger.yml

----
-# Error: gitlab.AlertBoxDanger
-#
-# Makes sure DANGER: alert boxes follow standard formatting.
-#
-# For a list of all options, see https://errata-ai.gitbook.io/vale/getting-started/styles
-extends: substitution
-message: "DANGER: alert boxes must be of the format 'DANGER: **Warning:**'. 'Warning' can be replaced with 'Important', 'Deprecated', or 'Required'."
-link: https://docs.gitlab.com/ee/development/documentation/styleguide.html#alert-boxes
-level: error
-nonword: true
-scope: raw
-swap:
-  'DANGER: *?\*\*.*\*\*': 'DANGER: \*\*(?:Warning|Important|Deprecated|Required):\*\*'

doc/.vale/gitlab/AlertBoxNoteTip.yml

----
-# Error: gitlab.AlertBoxNoteTip
-#
-# Makes sure NOTE: and TIP: alert boxes follow standard formatting.
-#
-# For a list of all options, see https://errata-ai.gitbook.io/vale/getting-started/styles
-extends: substitution
-message: "NOTE: and TIP: alert boxes must be of the format 'NOTE:' or 'TIP: **Tip:**"
-link: https://docs.gitlab.com/ee/development/documentation/styleguide.html#alert-boxes
-level: warning
-nonword: true
-scope: raw
-swap:
-  'NOTE: *?\*\*.*\*\*': 'NOTE: \*\*Note:\*\*'
-  'TIP: *?\*\*.*\*\*': 'TIP: \*\*Tip:\*\*'

doc/.vale/gitlab/AlertBoxStyle.yml

----
-# Error: gitlab.AlertBoxStyle
-#
-# Makes sure alert boxes follow standard formatting.
-#
-# Checks for 2 formatting issues:
-# - Alert boxes with the note text on the same line
-# - Alert boxes using blockquote formatting, like "> **Note:**"
-#
-# For a list of all options, see https://errata-ai.gitbook.io/vale/getting-started/styles
-extends: existence
-message: 'Alert box "%s" must use the formatting in the style guide.'
-link: https://docs.gitlab.com/ee/development/documentation/styleguide.html#alert-boxes
-level: error
-scope: raw
-raw:
-  - '(\n(NOTE|TIP|CAUTION|DANGER): \*\*.*\*\*.+)|'
-  - '((\n[> ]*(\*){1,2}(NOTE|Note|note|TIP|Tip|tip|CAUTION|Caution|caution|DANGER|Danger|danger):(\*){1,2}))'