Fix out-of-bounds read in EmbedLayerNormalization shape inference for scalar beta (#32610)
### Description
`EmbedLayerNormalizationShapeInference` validated the `beta` input's
rank using the wrong shape: `beta_dims` was aliased to
`gamma_shape.dim()` instead of `beta_shape.dim()`. As a result, a rank-1
`gamma` would let the rank check pass
even when `beta` is a 0-dim scalar, and execution reached
`beta_shape.dim(0).dim_value()` — an unchecked protobuf repeated-field
access on an empty `dim` list, causing an out-of-bounds read during
session load, before provider/kernel assignment.
### Fix
- Alias `beta_dims` to `beta_shape.dim()` so the rank check guards the
correct input; a scalar `beta` is now rejected via
`fail_shape_inference` instead of reaching the OOB access. This matches
the adjacent `gamma` validation.
- Correct the `gamma` error message ("2 dimension" → "1 dimension") to
reflect the actual check