Auto merge of #115898 - onur-ozkan:config-change-tracking, r=Mark-Simulacrum

bootstrap major change detection implementation

The use of `changelog-seen` and `bootstrap/CHANGELOG.md` has not been functional in any way for many years. We often do major/breaking changes but never update the changelog file or the `changelog-seen`. This is an alternative method for tracking major or breaking changes and informing developers when such changes occur.

Example output when bootstrap detects a major change:
![image](https://github.com/rust-lang/rust/assets/39852038/ee802dfa-a02b-488b-a433-f853ce079b8a)

1 files changed, 1 insertions, 1 deletions

diff --git a/src/bootstrap/bootstrap_test.py b/src/bootstrap/bootstrap_test.py
index dc06a4c9734..fefd6b18739 100644
--- a/src/bootstrap/bootstrap_test.py
+++ b/src/bootstrap/bootstrap_test.py
@@ -103,7 +103,7 @@ class GenerateAndParseConfig(unittest.TestCase):
     """Test that we can serialize and deserialize a config.toml file"""
     def test_no_args(self):
         build = serialize_and_parse([])
-        self.assertEqual(build.get_toml("changelog-seen"), '2')
+        self.assertEqual(build.get_toml("change-id"), '115898')
         self.assertEqual(build.get_toml("profile"), 'dist')
         self.assertIsNone(build.get_toml("llvm.download-ci-llvm"))