Bug: [no-unnecessary-type-assertion] (regression) false positives on template literals with no expressions

[abrahamguo]

Before You File a Bug Report Please Confirm You Have Done The Following...

• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I have searched for related issues and found none that matched my issue.
• I have read the FAQ and my problem is not listed.

Playground Link

https://typescript-eslint.io/play/#ts=5.4.3&fileType=.tsx&code=DYUwLgBAhhC8EAMoOgZwgYwPYDtVgG4AoUSAIzggHIyq1Nd8Cg&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6Jge1tiacTJTIAhtEK0ipWkOTJE0fJQ5N0UOdA7RI4MAF8QOoA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3TgwAXxCSgA&tokens=false

Repro Code

let a = `a` as const;
let b = 'b' as const;

ESLint Config

module.exports = {
  parser: "@typescript-eslint/parser",
  rules: {
    "@typescript-eslint/no-unnecessary-type-assertion": "error"
  },
};

Expected Result

No lint errors should be reported, as the type assertions are meaningful.

Actual Result

The type assertion on the backtick strings is reported as unnecessary, while the quoted string is not reported.

Additional Info

A regression from #8740