[UXE-5977] hotfix: fixed variable names in edge firewall

[HerbertJulio]

Bug fix

Explain what was fixed and the correct behavior.

This pull request includes changes to the FormFieldsEdgeFirewallRulesEngine.vue file to improve the maintainability and readability of the code by using template literals for specific string values.

Codebase improvements:

• src/views/EdgeFirewallRulesEngine/FormFields/FormFieldsEdgeFirewallRulesEngine.vue: Replaced hardcoded string values with template literals for operator and variable checks to improve maintainability and reduce the risk of errors.

Does this PR introduce UI changes? Add a video or screenshots here.

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Checklist

Make sure your pull request fits the checklist below (when applicable):

• The issue title follows the format: [ISSUE_CODE] bug: TITLE
• Commits are tagged with the right word (feat, test, refactor, etc)
• Application responsiveness was tested to different screen sizes
• New tests are added to prevent the same issue from happening again
• UI changes are validated by a team designer
• Code is formatted and linted
• Tags are added to the PR

These changes were tested on the following browsers:

• Chrome
• Edge
• Firefox
• Safari

The base branch was changed.