Delete references to the Debian-bundled Python

We should now be able to use the rules_python version for everything.
There's no need to keep the old stuff around.

Signed-off-by: Philipp Schrader <philipp.schrader@gmail.com>
Change-Id: I75b1764d1d98c17832bfd0146c958db96d54ae48
diff --git a/tools/python/BUILD b/tools/python/BUILD
index 78203bc..8e410e5 100644
--- a/tools/python/BUILD
+++ b/tools/python/BUILD
@@ -1,11 +1,28 @@
 load("@rules_python//python:defs.bzl", "py_runtime_pair")
 load("@rules_python//python:pip.bzl", "compile_pip_requirements")
 
+# Invoke this via "bazel run //tools/python:requirements.update".
+compile_pip_requirements(
+    name = "requirements",
+    requirements_in = "requirements.txt",
+    requirements_txt = "requirements.lock.txt",
+    tags = [
+        # The test pings pypi.org to make sure that the lock file matches the
+        # requirements file.
+        "requires-network",
+        # The test causes some packages' setup.py to be executed which can
+        # execute arbitrary code. Sometimes they look for compilers etc. That's
+        # not good for our hermeticity assumptions. Disable the test lock file
+        # test for now.
+        "manual",
+    ],
+)
+
 py_runtime(
     name = "python3_runtime",
     files = [
         "runtime_binary.sh",
-        "@python_repo//:all_files",
+        "@python3_9_x86_64-unknown-linux-gnu//:files",
     ],
     interpreter = "runtime_binary.sh",
     python_version = "PY3",
@@ -26,60 +43,11 @@
     target_compatible_with = [
         "@platforms//cpu:x86_64",
         "@platforms//os:linux",
-        "//tools/platforms/python:debian_bundled_python",
     ],
     toolchain = ":py_runtime",
     toolchain_type = "@rules_python//python:toolchain_type",
 )
 
-# Invoke this via "bazel run //tools/python:requirements.update".
-compile_pip_requirements(
-    name = "requirements",
-    requirements_in = "requirements.txt",
-    requirements_txt = "requirements.lock.txt",
-    tags = [
-        # The test pings pypi.org to make sure that the lock file matches the
-        # requirements file.
-        "requires-network",
-        # The test causes some packages' setup.py to be executed which can
-        # execute arbitrary code. Sometimes they look for compilers etc. That's
-        # not good for our hermeticity assumptions. Disable the test lock file
-        # test for now.
-        "manual",
-    ],
-)
-
-py_runtime(
-    name = "upstream_python3_runtime",
-    files = [
-        "runtime_binary.sh",
-        "@python3_9_x86_64-unknown-linux-gnu//:files",
-    ],
-    interpreter = "runtime_binary.sh",
-    python_version = "PY3",
-)
-
-py_runtime_pair(
-    name = "upstream_py_runtime",
-    py2_runtime = None,
-    py3_runtime = ":upstream_python3_runtime",
-)
-
-toolchain(
-    name = "upstream_python_toolchain",
-    exec_compatible_with = [
-        "@platforms//cpu:x86_64",
-        "@platforms//os:linux",
-    ],
-    target_compatible_with = [
-        "@platforms//cpu:x86_64",
-        "@platforms//os:linux",
-        "//tools/platforms/python:upstream_bundled_python",
-    ],
-    toolchain = ":upstream_py_runtime",
-    toolchain_type = "@rules_python//python:toolchain_type",
-)
-
 py_binary(
     name = "mirror_pip_packages",
     srcs = ["mirror_pip_packages.py"],