Remove padding_embedding.pt — these ship with the inference code repo

Per-DiT learned padding embeddings (4 KB each) are constants tied to the model
architecture but tiny. Moving them out of this engines repo and into the inference
code repo's runtime/padding_embeddings/ alongside the tokenizer + num_conditioner.

tensorRT/sa3-m/padding_embedding.pt

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:63aa7c591786ff515371f2ae0bcec3dea4d75fe22f7a5d88c786a222c8d9c62c
-size 4302

tensorRT/sa3-sm-music/padding_embedding.pt

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:9e9b6a46c5d3fb07761378a94d6ea9bfc6312d1b18f4e106875d5c14e46b6bbb
-size 4302

tensorRT/sa3-sm-sfx/padding_embedding.pt

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:3f3f55bbd085051b506e94f6c7e651e78eaddb3d444f493888e747f348bd6549
-size 4302