feat(nimbus): add advanced targeting for win10 existing users needing… (#15639)

To support the [Win10 EoS communicate privacy value
experiment](https://docs.google.com/document/d/1A43ptw9LQlhF2pR7mcbt_mCrJx9zuaNEHYs1PhJBT2A/edit?tab=t.0)
this commit adds advanced targeting that covers:
- Win10 users
- Profile age 28 days and older
- Is NOT set to default

---------

Co-authored-by: Jared Lockhart <119884+jaredlockhart@users.noreply.github.com>

Author: sarahhjchung

experimenter/experimenter/targeting/constants.py

@@ -1165,6 +1165,17 @@ def __post_init__(self):
     application_choice_names=(Application.DESKTOP.name,),
 )
 
+WIN10_EXISTING_USERS_NEED_DEFAULT = NimbusTargetingConfig(
+    name="Windows 10 existing users needing default",
+    slug="win10_existing_users_need_default",
+    description=("Windows 10 users with profiles older than 28 days needing default"),
+    targeting=f"{PROFILE28DAYS} && {WIN10_NEED_DEFAULT.targeting}",
+    desktop_telemetry="",
+    sticky_required=False,
+    is_first_run_required=False,
+    application_choice_names=(Application.DESKTOP.name,),
+)
+
 GUIDANCE_NOTIFICATION_GIF_EXPERIMENT = NimbusTargetingConfig(
     name="Guidance notification GIF experiment",
     slug="guidance_notification_gif_experiment",