google-cloud-sdk: prefer using a pythonEnv vs just a search path

Previously only direct dependencies were available in the python search
path. Transitive dependencies would not be available and thus a few
features would not work due to import errors. Those import errors were
being caugth and gave a (wrong) hint why it wouldn't work. By using
`python.withPackages` instead of the crafted search path with only the
direct dependencies those missing feature should now be working.

See issue #67094 for details on the observed errors.

Fixes #67094

pkgs/tools/admin/google-cloud-sdk/default.nix

@@ -13,7 +13,7 @@
 let
   pythonInputs = [ cffi cryptography pyopenssl crcmod ]
                  ++ lib.optional (with-gce) google-compute-engine;
-  pythonPath = lib.makeSearchPath python.sitePackages pythonInputs;
+  pythonEnv = python.withPackages (_: pythonInputs);
 
   baseUrl = "https://dl.google.com/dl/cloudsdk/channels/rapid/downloads";
   sources = name: system: {
@@ -53,8 +53,8 @@ in stdenv.mkDerivation rec {
         programPath="$out/google-cloud-sdk/bin/$program"
         binaryPath="$out/bin/$program"
         wrapProgram "$programPath" \
-            --set CLOUDSDK_PYTHON "${python}/bin/python" \
-            --prefix PYTHONPATH : "${pythonPath}"
+            --set CLOUDSDK_PYTHON "${pythonEnv}/bin/python" \
+            --prefix PYTHONPATH : "${pythonEnv}/${python.sitePackages}"
 
         mkdir -p $out/bin
         ln -s $programPath $binaryPath