#7664 destroys the y-component of magnetic moment

[maki49]

Describe the bug

Before #7664, this symmetry-off Mn3Sn case with in-plane 120° AFM converges correctly to AMAG=19.8. In contrast, it converges to x-colinear state with AMAG=15.2 after #7664, that is, the y-component of magmom collapses.
Mn3Sn-7664-bug.zip

#7664 intended to change the $m_y$ convention consistent with the textbook Pauli matrix. However, DensityMatrix actually stores conj(D)=conj(c)*c instead of D=c*conj(c) to fit the col-major nature of BLAS (and conj(D)=transpose(D) are used as row-major D everywhere), the easiest way to fix the bug is to use the conjugated convention individually at the non-BLAS operators like m_y, i.e. to revert the change of func_xyz_to_updown in #7664.

Expected behavior

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To Reproduce

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Environment

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Additional Context

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