treewide: remove FHSEnv

To remove the FHSenv, we have to patch rules_python to use
/usr/bin/env to resolve the path to bash instead of hardcoding it.
Additionally, we now bring a Nix-compatible Bazel 8.

Change-Id: Id51e7748eea6dd77185f43a52fe45b5110ba4a2b
Reviewed-on: https://review.monogon.dev/c/monogon/+/4427
Tested-by: Jenkins CI
Reviewed-by: Jan Schär <jan@monogon.tech>
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
Reviewed-by: Leopold Schabel <leo@monogon.tech>
diff --git a/third_party/nix/pkgs/bazel_8/system.bazelrc b/third_party/nix/pkgs/bazel_8/system.bazelrc
new file mode 100644
index 0000000..6684e33
--- /dev/null
+++ b/third_party/nix/pkgs/bazel_8/system.bazelrc
@@ -0,0 +1,4 @@
+startup --server_javabase=@serverJavabase@
+
+# load default location for the system wide configuration
+try-import /etc/bazel.bazelrc