feat: remove helpers/filters from nuxt-theme and commercetools

[k-malkowski]

Related Issues

closes #5620

Short Description of the PR

Removed helpers/filters from @vue-storefront/nuxt-theme and @vue-storefront/commercetools-theme because they are useless now.

Pull Request Checklist

• I have updated the Changelog (V1) v2 and mentioned all breaking changes in the public API.
• I have documented all new public APIs and made changes to existing docs mentioning the parts I've changed so they're up to date.
• I have tested my Pull Request on production build and (to my knowledge) it works without any issues

• I have followed naming conventions

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[coveralls]

Pull Request Test Coverage Report for Build 658925659

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+4.6%) to 85.071%

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Totals
Change from base Build 656941134:	4.6%
Covered Lines:	815
Relevant Lines:	944

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 665020090

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 7 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.4%) to 80.121%

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Files with Coverage Reduction	New Missed Lines	%
packages/commercetools/api-client/src/helpers/commercetoolsLink/linkHandlers.ts	1	90.63%
packages/core/cli/src/scripts/generateTemplates/index.ts	6	0%

Totals
Change from base Build 656941134:	-0.4%
Covered Lines:	1503
Relevant Lines:	1747

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💛 - Coveralls

[k-malkowski]

The documentation (next) has been already updated, so I think everything is good now. What about this error in deploy PR? @filipsobol

[filipsobol]

The documentation (next) has been already updated, so I think everything is good now. What about this error in deploy PR? @filipsobol

Can you add a changelog, please? https://docs.vuestorefront.io/v2/contributing/creating-changelog.html

[filrak]

Thanks, merging!