fix: fix dsv3 by disable mtp

[yuki-97]

fix the following release/perf tests:

h100:

• grpo-deepseek-v3-64n8g-async-1off
• grpo-deepseek-v3-32n8g
• grpo-dapomath17k-dsv3-megatron
• grpo-deepseek-v3-64n8g-fp8-async-1off
• dapo-deepseek-v3-64n8g (this one is unstable at init)

gb200:

• grpo-deepseek-v3-32n4g
• grpo-deepseek-v3-64n4g-async-1off
• grpo-dapomath17k-dsv3-32n4g-megatron (still running)

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[yuki-97]

/ok to test f5e6325