start_date and end_date in variation seed is not respected

[btlechowski]

start_date and end_date in variation seed is ignored.

Steps to Reproduce

1. Make sure that the study is enabled on griffin.
2. Clean profile
3. Use staging seed variation
4. Run Brave
5. Restart Brave:
6. Open brave://version
7. Scroll down to Active Variations

Actual result:

The study is enabled:

DefaultAdNotificationsPerHour=10/MaximumAdNotificationsPerDay=100/MaximumInlineContentAdsPerHour=6/MaximumInlineContentAdsPerDay=20/AdServingVersion=2

Expected result:

The study is enabled:

DefaultAdNotificationsPerHour=10/MaximumAdNotificationsPerDay=100/MaximumInlineContentAdsPerHour=6/MaximumInlineContentAdsPerDay=20/MaximumNewTabPageAdsPerDay=0/AdServingVersion=2

Reproduces how often:

Easily reproduced

Version/Channel Information:

Brave	1.51.80 Chromium: 112.0.5615.49 (Official Build) beta (64-bit)
Revision	bd2a7bcb881c11e8cfe3078709382934e3916914-refs/branch-heads/5615@{#936}
OS	Ubuntu 18.04 LTS

cc @tmancey @aseren @iefremov @goodov

[goodov]

@btlechowski start_date/end_date now work as expected.

This is what I see in debug logs:

[196808:202444:0418/214043.699:VERBOSE1:study_filtering.cc(352)] Filtered out study BraveAds.AdServingStudy due to end date.
[196808:202444:0418/214043.699:VERBOSE1:study_filtering.cc(403)] Kept study BraveAds.AdServingStudy.
[196808:202444:0418/214043.699:VERBOSE1:study_filtering.cc(346)] Filtered out study BraveAds.AdServingStudy due to start date.

this is brave://version:

[btlechowski]

Verification passed on

Brave	1.50.121 Chromium: 112.0.5615.138 (Official Build) (64-bit)
Revision	2258f2fcaeb07bc95c992b7ca47f0b43ead9865c-refs/branch-heads/5615@{#1282}
OS	Ubuntu 18.04 LTS

Verified start_date and end_date are supported as study that is only available on 18th Apr is enabled on that date

Verified study with MaximumNewTabPageAdsPerDay=0 is enabled

Verified NTPSI was not served:

[28916:28916:0419/145856.808365:VERBOSE2:permission_rule_util.cc(25)] You have exceeded the allowed new tab page ads per day
[28916:28916:0419/145856.808638:VERBOSE1:new_tab_page_ad_serving.cc(65)] New tab page ad not served: Not allowed due to permission rules

[kjozwiak]

Going to move this into 1.51.x even though it technically will go live earlier via 1.50.x once it's pushed to production via brave/brave-variations#596. But 1.51.x is the next major release so we'll add it into this milestone.