[distributions] Apply weaker test for `torch.distributions.wishart.Wishart` to match the level in other libraries. (#76525)
Follow up PR for #76160
- Removed the tests for the Wishart distribution in the unstable region, `ndim - 1 < df < ndim` to `df ~ ndim + 1`.
- Apply same perturbation for the random variables with Postive Semi-definite constraint equally to the Positive Definite constraint.
- Fix seeds in randomized tests.
cc @neerajprad
Pull Request resolved: https://github.com/pytorch/pytorch/pull/76525
Approved by: https://github.com/neerajprad
