Disable group offset for tokamax gmm

[NuojCheng]

Description

This PR fixes use_tokamax_gmm=true code path when use_ring_of_expert=false. It also adds an tokamax gmm AOT test.

Tests

CI tests and tokamax gmm AOT test (but skipped due to b/489205940)

Local test: https://paste.googleplex.com/6403591735738368. The compilation was successful.

Checklist

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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