fix: remove trailing forward slash when resolving workspace root link in runfiles MANIFEST

[gregmagolan]

This regressed at some point between 3.3 and 4.4 releases.

The problem appears specific to binary targets (not build targets) that resolve from the MANIFEST.

Repro here: https://github.com/ssilve1989/bazel-playground on bug/link_workspace_root branch

❯ bazelisk run //packages/examples/node/helloworld
INFO: Invocation ID: a0fce2a3-518b-438c-a490-7614f1680c76
INFO: Analyzed target //packages/examples/node/helloworld:helloworld (1 packages loaded, 4 targets configured).
INFO: Found 1 target...
Target //packages/examples/node/helloworld:helloworld up-to-date:
  dist/bin/packages/examples/node/helloworld/helloworld.sh
  dist/bin/packages/examples/node/helloworld/helloworld_loader.js
  dist/bin/packages/examples/node/helloworld/helloworld_require_patch.js
INFO: Elapsed time: 3.259s, Critical Path: 2.96s
INFO: 5 processes: 1 internal, 4 darwin-sandbox.
INFO: Build completed successfully, 5 total actions
INFO: Build completed successfully, 5 total actions
Error: Cannot find module 'playground/packages/common/math/math'
Require stack:
- /private/var/tmp/_bazel_SSilvestri/0b924cd44f9ad5151fc11486fa79c02d/execroot/playground/bazel-out/darwin-fastbuild/bin/packages/examples/node/helloworld/helloworld.sh.runfiles/playground/packages/examples/node/helloworld/main.js
    at Function.Module._resolveFilename (node:internal/modules/cjs/loader:933:15)
    at Function.Module._load (node:internal/modules/cjs/loader:778:27)
    at Module.require (node:internal/modules/cjs/loader:1005:19)
    at require (node:internal/modules/cjs/helpers:102:18)
    at Object.<anonymous> (packages/examples/node/helloworld/main.js:3:16)
    at Module._compile (node:internal/modules/cjs/loader:1101:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1153:10)
    at Module.load (node:internal/modules/cjs/loader:981:32)
    at Function.Module._load (node:internal/modules/cjs/loader:822:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12)