fc.agent maintenance reboots: warm -> cold is not significant

@ctheune and I have decided that there is no good reason for making the
change of a warm to a cold reboot trigger a reschedule and customer
notification.

PL-133301

changelog.d/20241221_120758_PL-133301-reboot-significance_scriv.md

@@ -0,0 +1,20 @@
+<!--
+
+A new changelog entry.
+
+Delete placeholder items that do not apply. Empty sections will be removed
+automatically during release.
+
+Leave the XX.XX as is: this is a placeholder and will be automatically filled
+correctly during the release and helps when backporting over multiple platform
+branches.
+
+-->
+
+### Impact
+
+
+
+### NixOS XX.XX platform
+
+- Changing a planned warm reboot to a cold reboot by merging does not trigger customer notifications and reschedule the maintenance window anymore. (PL-133301)

pkgs/fc/agent/fc/maintenance/activity/reboot.py

@@ -64,7 +64,7 @@ def merge(self, other):
                 "merge-reboot-warm-to-cold",
                 help=(
                     "merging a cold reboot into a warm reboot results in a "
-                    "cold reboot. This is a significant change."
+                    "cold reboot."
                 ),
             )
 
@@ -73,6 +73,5 @@ def merge(self, other):
             return ActivityMergeResult(
                 self,
                 is_effective=True,
-                is_significant=True,
                 changes={"before": RebootType.WARM, "after": RebootType.COLD},
             )

pkgs/fc/agent/fc/maintenance/activity/tests/test_reboot.py

@@ -84,13 +84,13 @@ def test_reboot_merge_warm_is_an_insignificant_update(warm):
     assert not result.changes
 
 
-def test_reboot_merge_cold_is_an_significant_update(warm, cold):
+def test_reboot_merge_cold_is_an_insignificant_update(warm, cold):
     original = warm
     result = original.merge(cold)
     assert result.merged is original
     assert result.merged.reboot_needed == RebootType.COLD
     assert result.is_effective is True
-    assert result.is_significant is True
+    assert result.is_significant is False
     assert result.changes == {"before": "reboot", "after": "poweroff"}