Drop explicit tool installation in the dev container (pythonGH-138211)

This is now handled upstream in the dev container image itself.
(cherry picked from commit d910b93)

Co-authored-by: Brett Cannon <brett@python.org>

Author: brettcannon

.devcontainer/devcontainer.json

@@ -5,9 +5,6 @@
         "dnf",
         "install",
         "-y",
-        "which",
-        "zsh",
-        "fish",
         // For umask fix below.
         "/usr/bin/setfacl"
     ],