Cleanup M3 token templates for theme lookups

[TahaTesser]

fixes #117933

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
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• I listed at least one issue that this PR fixes in the description above.
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• I added new tests to check the change I am making, or this PR is test-exempt.
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[flutter-dashboard]

It looks like this pull request may not have tests. Please make sure to add tests before merging. If you need an exemption to this rule, contact Hixie on the #hackers channel in Chat (don't just cc him here, he won't see it! He's on Discord!).

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[guidezpl]

Nice cleanup!

[Hixie]

test-exempt: code refactor with no semantic change