Fix: Allow to fetch tax class ID for NOT LOGGED IN customer group

[thomas-kl1]

Description (*)

When using \Magento\Catalog\Helper\Data::getTaxPrice to fetch price, tax details are miscalculated for context with guest users.

Here the group id 0 was interpreted as NULL while it shouldn't.

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• README.md files for modified modules are updated and included in the pull request if any README.md predefined sections require an update
• All automated tests passed successfully (all builds are green)

Resolved issues:

1. resolves [Issue] Fix: Allow to fetch tax class ID for NOT LOGGED IN customer group #39850: Fix: Allow to fetch tax class ID for NOT LOGGED IN customer group

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[engcom-Hotel]

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