Bug [ring]: bad distribution for large norm discrete Gaussian sampling

[Pro7ech]

The distribution of the values sampled by the Gaussian sampler when using large norm (when $\sigma > 2^{53}$ or when $\mathcal{B} > 2^{64}-1$) does not look like a smooth Gaussian:

In orange the expected PDF, in blue the actual PDF for $\sigma = 2^{128}$.

[qantik]

Hi, can you make this issue compliant with the template?

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Does this issue persist with the latest release?

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Reproducibility