[geometry] Hotfix "Move CalcBarycentric ..."

[jwnimmer-tri]

The requires clause was a problem for Doxygen:

drake/geometry/proximity/triangle_surface_mesh.h:299: error: argument 'p_MQ' of command @param is not found in the argument list of TriangleSurfaceMesh< T >::CalcBoundingBox() const
drake/geometry/proximity/triangle_surface_mesh.h:299: error: argument 't' of command @param is not found in the argument list of TriangleSurfaceMesh< T >::CalcBoundingBox() const
drake/geometry/proximity/volume_mesh.h:249: error: argument 'e' of command @param is not found in the argument list of VolumeMesh< T >::Equal(const VolumeMesh< T > &mesh, double vertex_tolerance=0) const
drake/geometry/proximity/volume_mesh.h:249: error: argument 'p_MQ' of command @param is not found in the argument list of VolumeMesh< T >::Equal(const VolumeMesh< T > &mesh, double vertex_tolerance=0) 

Amends #23527.

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This change is 

[jwnimmer-tri]

@drake-jenkins-bot linux-noble-unprovisioned-gcc-bazel-experimental-documentation please

[SeanCurtis-TRI]

X2

+a:@SeanCurtis-TRI

@SeanCurtis-TRI reviewed 4 of 4 files at r1, all commit messages.
Reviewable status: complete! all discussions resolved, LGTM from assignee SeanCurtis-TRI(platform)