chore: enable exec tools toolchain by default (#2308)

This enables the exec tools toolchain by default. The flag to disable it
is left
available as an escape hatch.

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 662a557..867ce12 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -35,6 +35,9 @@
   (or equivalent).
 * (toolchains) `py_runtime.implementation_name` now defaults to `cpython`
   (previously it defaulted to None).
+* (toolchains) The exec tools toolchain is enabled by default. It can be
+  disabled by setting
+  {obj}`--@rules_python//python/config_settings:exec_tools_toolchain=disabled`.
 * (deps) stardoc 0.6.2 added as dependency.
 
 ### Fixed

python/config_settings/BUILD.bazel

diff --git a/python/config_settings/BUILD.bazel b/python/config_settings/BUILD.bazel
index b55213b..c530afe 100644
--- a/python/config_settings/BUILD.bazel
+++ b/python/config_settings/BUILD.bazel
@@ -42,7 +42,7 @@
 
 string_flag(
     name = "exec_tools_toolchain",
-    build_setting_default = ExecToolsToolchainFlag.DISABLED,
+    build_setting_default = ExecToolsToolchainFlag.ENABLED,
     values = sorted(ExecToolsToolchainFlag.__members__.values()),
     # NOTE: Only public because it is used in py_toolchain_suite from toolchain
     # repositories