Make DMMHA kernel inside MHA optional for Whisper (#25166)
### Description
This PR sets adding support for the `DecoderMaskedMultiHeadAttention`
(DMMHA) kernel inside `MultiHeadAttention` (MHA) to false by default.
### Motivation and Context
The models containing the extra inputs for DMMHA (i.e.
`past_sequence_length` and `cache_indirection`) have some runtime
issues. Additionally, not all execution providers implement the DMMHA
kernel inside MHA and will therefore not support these extra inputs.
