[llvm] [NFC][IR2Vec] Removing Dimension from `Embedder::Create` (PR #142486)

[S. VenkataKeerthy via llvm-commits]

svkeerthy wrote:

That's right. Having to pass dimension would complicate the consumers in a way that they are expected to know the dimension apriori (which in a way necessitates tracking the dimension).

https://github.com/llvm/llvm-project/pull/142486