fix ep weight gradnorm/num_zero calculation error for muon

[FDecaYed]

What does this PR do ?

With muon, expert weight are no longer belong to a separate optimizer instance and thus chainedoptimizer gradnorm/zero calculation was wrong reducing among EP ranks. This PR separate expert weights out into separate muon instance to fix that.
The issue causes dp rank weight diverge and was caught with checkpoint loading test. turn the broken test back on

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flowchart LR
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[FDecaYed]

/ok to test d1cf84f

[FDecaYed]

/ok to test b6f763b

[FDecaYed]

/ok to test f14b678

[FDecaYed]

/ok to test e605a76

[FDecaYed]

/ok to test 1ec5636

[skyw]

muon change LGTM.
Test cases change need to be reviewed by folks familiar with the manner.

[BoxiangW]

/ok to test 1ec5636

[BoxiangW]

/ok to test 1ec5636