Fix character count behaviour tests instantiating twice

[colinrotherham]

Our tests were creating 2x new CharacterCount() instances on the same HTML markup

Split out from #4561

[github-actions]

📋 Stats

File sizes

File	Size
dist/govuk-frontend-development.min.css	112.47 KiB
dist/govuk-frontend-development.min.js	38.58 KiB
packages/govuk-frontend/dist/govuk/all.bundle.js	78.74 KiB
packages/govuk-frontend/dist/govuk/all.bundle.mjs	73.99 KiB
packages/govuk-frontend/dist/govuk/all.mjs	3.86 KiB
packages/govuk-frontend/dist/govuk/govuk-frontend-component.mjs	359 B
packages/govuk-frontend/dist/govuk/govuk-frontend.min.css	112.46 KiB
packages/govuk-frontend/dist/govuk/govuk-frontend.min.js	38.57 KiB
packages/govuk-frontend/dist/govuk/i18n.mjs	5.38 KiB

Modules

File	Size
all.mjs	70.32 KiB
components/accordion/accordion.mjs	21.67 KiB
components/button/button.mjs	4.7 KiB
components/character-count/character-count.mjs	21.24 KiB
components/checkboxes/checkboxes.mjs	5.83 KiB
components/error-summary/error-summary.mjs	6.57 KiB
components/exit-this-page/exit-this-page.mjs	16.08 KiB
components/header/header.mjs	4.46 KiB
components/notification-banner/notification-banner.mjs	4.93 KiB
components/radios/radios.mjs	4.83 KiB
components/skip-link/skip-link.mjs	4.39 KiB
components/tabs/tabs.mjs	10.16 KiB

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