show background image should be default on

[rebron]

Test plan

1. New profile/user. New tab page background images should be on by default.
2. Existing user 67 and lower. Upgrade to 68, New tab page background should have images.

Description

With fix for #4523, background images is defaulted off.

Background images should be shown by default.

It's a jarring change for existing users, who had background images previously.

Will need to test on upgrade that user preference is maintained.

1. If user selects background images off, on upgrade, background images should still be off.
2. If user selects background images on (default state but if users toggle back to background images on after previously selecting background images off), background images should still be on.

current screen for new users and existing user's updating

expected screen for new users and existing user's updating (but with their stats/top tiles info intact)

[srirambv]

The new setting to disable background image isn't intuitive and can be easily missed. @karenkliu how about adding a one time focus with tooltip is shown on opening a new tab after the fix goes into the release?

[karenkliu]

@srirambv Originally I wanted the panel to actually be open the first time a user landed on the page, but @bradleyrichter decided it's better to let user discovery take its course.

[GeetaSarvadnya]

Verification passed on

Brave	0.68.113 Chromium: 76.0.3809.62 (Official Build) beta (64-bit)
Revision	7b77856b3aa34d72f246d12340fc1ded8b2c0e83-refs/branch-heads/3809@{#798}
OS	Windows 10 OS Version 1803 (Build 17134.523)

• Verified the test plan from make background image on NTP default enabled brave-core#2756
  • Verified that background images ON in NTP by default in a new profile 0.68.113
  • Verified that background images ON in NTP when the profile is upgraded from 0.67.115 to 0.68.113

Verification passed on

Brave	0.68.113 Chromium: 76.0.3809.62 (Official Build) beta (64-bit)
Revision	7b77856b3aa34d72f246d12340fc1ded8b2c0e83-refs/branch-heads/3809@{#798}
OS	Ubuntu 18.04 LTS

• Verified the test plan from make background image on NTP default enabled brave-core#2756
  • Verified that background images ON in NTP by default in a new profile 0.68.113
  • Verified that background images ON in NTP when the profile is upgraded from 0.67.115 to 0.68.113

Verified passed with

Brave	0.68.116 Chromium: 76.0.3809.87 (Official Build) beta (64-bit)
Revision	111fe1e15d5ced26080a7dc239bcfe70f6c49aad-refs/branch-heads/3809@{#967}
OS	Mac OS X

• Verified test plan from description:
  • Clean profile with 0.68.116. Verified NTP had setting for background images ON.
  • Installed 0.67.112. Upgraded to 0.68.116. Verified NTP had setting for background images ON.