Remove unnecessary eval to fix PATH variables containing a space (#2087)

Fixes #2086

As far as I can tell, this `eval` is unnecessary at best, and breaks
with certain edge cases, like `PATH` (or other referenced variables)
which include a space.

I'm not very familiar with this repo, but if there's a way to add a test
for this I'd be happy to do it.

Co-authored-by: UebelAndre <[email protected]>

crate_universe/private/crates_vendor.bzl

@@ -18,7 +18,7 @@ fi
 # If you provide an empty path, bazel starts itself with
 # --default_system_javabase set to the empty string, but if you provide a path,
 # it may set it to a value (eg. "/usr/local/buildtools/java/jdk11").
-eval exec env - BAZEL_REAL="${{BAZEL_REAL}}" BUILD_WORKSPACE_DIRECTORY="${{BUILD_WORKSPACE_DIRECTORY}}" PATH="${{PATH}}" {env} \\
+exec env - BAZEL_REAL="${{BAZEL_REAL}}" BUILD_WORKSPACE_DIRECTORY="${{BUILD_WORKSPACE_DIRECTORY}}" PATH="${{PATH}}" {env} \\
 "{bin}" {args} "$@"
 """