Fix displaying Special Price excluding tax

[magently]

Description

Whenever a Special Price and a Regular Price was displayed with tax and without, the amount of the Special Price without tax was changed into one equal to the amount of Regular Price without tax.

Fixed Issues (if relevant)

1. Old price excluding TAX is incorrectly replaced by JavaScript #11998: Old price excluding TAX is incorrectly replaced by JavaScript

Manual testing scenarios

Same as Fixed Issue

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)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-cicd2]

All committers have signed the CLA.

[magento-engcom-team]

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