Fix Brave Ads duplicate feature name and decouple features

[tmancey]

No description provided.

[btlechowski]

Verification passed on

Brave	1.53.99 Chromium: 114.0.5735.133 (Official Build) beta (64-bit)
Revision	fbfa2ce68d01b2201d8c667c2e73f648a61c4f4a-refs/branch-heads/5735@{#1270}
OS	Ubuntu 18.04 LTS

Verified test plan from brave/brave-core#18198

idle_time_threshold parameter of UserIdleDetection

set idle_time_threshold to 60s

[20776:20776:0620/170217.115589:VERBOSE6:user_activity_manager.cc(42)] Triggered event: 02 (0:0:900 s)
[20776:20776:0620/170317.890637:VERBOSE1:user_idle_detection.cc(42)] User is idle

Verified user is idle after 1 minute

notification_ad_timeout parameter of NotificationAds

notification ad was shown:

[17858:17858:0620/163952.661836:VERBOSE1:eligible_notification_ads_v2.cc(38)] Get eligible notification ads
[17858:17858:0620/163952.713571:VERBOSE1:eligible_notification_ads_v2.cc(124)] 20 eligible ads out of 20 ads
[17858:17858:0620/163952.714502:VERBOSE1:notification_ad_handler.cc(121)] Opportunity arose to serve a notification ad
[17858:17858:0620/163952.714878:VERBOSE1:notification_ad_serving.cc(127)] Found 1 eligible ads
[17858:17858:0620/163952.715099:VERBOSE1:notification_ad_serving.cc(200)] Served notification ad:
  placementId: e9afbb6e-bc7d-41d1-9a03-1773d828711a
  creativeInstanceId: 87173187-acb2-432b-a18d-a235f15f1c1c
  creativeSetId: 45ea5952-37ca-41f0-88c2-4b546b0e6f4b
  campaignId: 1c1ac828-db13-49bb-9128-090132044b7f
  advertiserId: ecbcc833-8b1d-4867-98f7-ad2341396ce8
  segment: untargeted
  title: Ad7
  body: Ad7
  targetUrl: https://brave.com/
[17858:17858:0620/163952.715919:VERBOSE6:ads_service_impl.cc(820)] Timeout notification ad with placement id e9afbb6e-bc7d-41d1-9a03-1773d828711a in 1 s
[17858:17858:0620/163952.716176:VERBOSE3:notification_ad_event_served.cc(19)] Served notification ad with placement id e9afbb6e-bc7d-41d1-9a03-1773d828711a and creative instance id 87173187-acb2-432b-a18d-a235f15f1c1c
[17858:17858:0620/163952.717897:VERBOSE9:client_state_manager.cc(492)] Saving client state
[17858:17858:0620/163952.718759:VERBOSE3:notification_ad_event_viewed.cc(19)] Viewed notification ad with placement id e9afbb6e-bc7d-41d1-9a03-1773d828711a and creative instance id 87173187-acb2-432b-a18d-a235f15f1c1c
[17858:17858:0620/163952.715919:VERBOSE6:ads_service_impl.cc(820)] Timeout notification ad with placement id e9afbb6e-bc7d-41d1-9a03-1773d828711a in 1 s

The notification ad was reached timeout and was closed

[17858:17858:0620/163953.737756:VERBOSE2:ads_service_impl.cc(837)] Timed-out notification ad with placement id e9afbb6e-bc7d-41d1-9a03-1773d828711a
[17858:17858:0620/163953.739628:VERBOSE3:notification_ad_event_timed_out.cc(16)] Timed out notification ad with placement id e9afbb6e-bc7d-41d1-9a03-1773d828711a and creative instance id 87173187-acb2-432b-a18d-a235f15f1c1c

custom ad notification is shown when CustomNotificationAds feature enabled