Stop applying buck2 specific string replace [7/7]

Summary:
In D63295973 these targets are translated explicitly within the BUCK file, and
this is no longer needed.

Reviewed By: bigfootjon

Differential Revision: D63333635

fbshipit-source-id: 0238277ef0199a4e5c72e065438a0e5121ae6bf9

shim/shims.bzl

@@ -306,12 +306,6 @@ def rust_protobuf_library(
         deps = [],
         test_deps = None,
         doctests = True):
-    if build_env:
-        build_env = {
-            k: _fix_dep_in_string(v)
-            for k, v in build_env.items()
-        }
-
     build_name = name + "-build"
     proto_name = name + "-proto"
 
@@ -410,11 +404,6 @@ def _fix_resources(resources):
 
     fail("Unexpected type {} for resources".format(type(resources)))
 
-def _fix_dep_in_string(x: str) -> str:
-    """Replace internal labels in string values such as env-vars."""
-    return (x
-        .replace("//buck2/", "root//"))
-
 # Do a nasty conversion of e.g. ("supercaml", None, "ocaml-dev") to
 # 'fbcode//third-party-buck/platform010/build/supercaml:ocaml-dev'
 # (which will then get mapped to `shim//third-party/ocaml:ocaml-dev`).