Fix incorrect template strings

[ocket8888]

This PR fixes an issue introduced in #6532 where some template strings use Javascript syntax like

`${variableName}`;

but they should use Python syntax like

f"{variable_name}"

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Which Traffic Control components are affected by this PR?

• GitHub Actions

What is the best way to verify this PR?

Run the GHA on your fork, verify the resulting PR

If this is a bugfix, which Traffic Control versions contained the bug?

• master

PR submission checklist

• This PR has tests
• This PR has documentation
• This PR has a CHANGELOG.md entry
• This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY