test: remove obsolete package manager selection assertions

Author: liangmiQwQ

crates/vp_cli_snapshots/tests/cli_snapshots/fixtures/shim_injected_tool_contracts/snapshots.toml

@@ -151,14 +151,6 @@ steps = [
   { argv = ["./system-shims/node", "assert-system-node-shim.cjs", "preload"], envs = [["PATH", "${VP_HOME}/bin${PATH_SEPARATOR}${workspace}/system-shims${PATH_SEPARATOR}/usr/bin${PATH_SEPARATOR}/bin"]], comment = "Preload output cannot corrupt the runtime probe, and npm/npx and their Node children still execute the preload" },
 ]
 
-[[case]]
-name = "explicit_npm_after_partial_path_reset"
-vp = "global"
-skip-platforms = ["windows"]
-steps = [
-  { argv = ["vp", "env", "exec", "--node", "22.18.0", "--npm", "10.5.0", "node", "assert-unix-shim-path.cjs", "partial"], comment = "After removing the injected npm from PATH, direct shims ignore VP_PACKAGE_MANAGER and use bundled npm" },
-]
-
 [[case]]
 name = "pinned_npm_after_partial_path_reset"
 vp = "global"