remove repo_name aliases

We have a bunch of 'repo_name' aliases, that [date back to being compatible with WORKSPACE dependencies](https://github.com/google/xls/blob/1378d5d1990d901ebf0461e9a51a2dc59e59acdc/MODULE.bazel#L49)

These can probably go now. I'll have a stab at it, removing them one-by-one

```
$ grep "bazel_dep.*repo_name" MODULE.bazel
bazel_dep(name = "abseil-cpp", version = "20260107.0", repo_name = "com_google_absl")
bazel_dep(name = "or-tools", version = "9.12", repo_name = "com_google_ortools")
bazel_dep(name = "protobuf", version = "33.0", repo_name = "com_google_protobuf")
bazel_dep(name = "zlib-ng", version = "2.3.3", repo_name = "llvm_zlib")
bazel_dep(name = "zstd", version = "1.5.7.bcr.1", repo_name = "llvm_zstd")
bazel_dep(name = "openroad", repo_name = "org_theopenroadproject")
bazel_dep(name = "fuzztest", version = "20260219.0", dev_dependency = True, repo_name = "com_google_fuzztest")
```

Start in MODULE.bazel and inspect the listed bazel_dep entries with repo_name aliases. Search the repository for each alias before removing them one by one, then verify that the dependencies still resolve and the project’s existing build or test commands pass.

Written by the indexing model from the issue text.