Make bookmarks bar visible on New Tabs Page by default

[simonhong]

As brave/brave-core#2869 is merged, user can choose whether bookmark bar is visible or not on NTP regardless of bookmark show option.

By default bookmark bar is off on NTP.
It should be visible by default.

[rebron]

Flagged this as a p2 to evaluate. We may want to include as part of hotfix with 68.x.
@kjozwiak @bsclifton

[GeetaSarvadnya]

Verification passed on

Brave	0.69.121 Chromium: 76.0.3809.132 (Official Build) beta (64-bit)
Revision	fd1acc410994a7a68ac25bc77513d443f3130860-refs/branch-heads/3809@{#1035}
OS	Windows 10 OS Version 1803 (Build 17134.523)

• Verified the test plan from Show bookmark bar on NTP by default brave-core#3251

Verification passed on

Brave	0.69.121 Chromium: 76.0.3809.132 (Official Build) beta (64-bit)
Revision	fd1acc410994a7a68ac25bc77513d443f3130860-refs/branch-heads/3809@{#1035}
OS	Ubuntu 18.04 LTS

• Verified the test plan from Show bookmark bar on NTP by default brave-core#3251
• Verified interaction with Show Bookmark Bar option

Verified passed with

Brave	0.69.123 Chromium: 76.0.3809.132 (Official Build) beta (64-bit)
Revision	fd1acc410994a7a68ac25bc77513d443f3130860-refs/branch-heads/3809@{#1035}
OS	Mac OS X

• Verified test plan from Show bookmark bar on NTP by default brave-core#3251
• Verified for clean install and upgrade profiles.

[jernejml]

This setting's default value should be set to off.
Scenario:

• you are preparing to share your screen (for example: presentation to your business partners or coworkers)
• you disable show bookmarks
• during presentation you open new tab
• your coworkers suddenly realize you like to read tabloid about celebrities or even worse