NTP SI link area overlaps shortcuts on smaller screens and windows or at high zoom levels

[kenherbert]

Description

When NTP SI link area is behind a shortcut, click will open the ad link, not the shortcut.

Steps to Reproduce

1. Open NTP
2. Set window size/zoom level so SI link area and shortcuts panel occupy same space
3. Click a shortcut that overlaps the SI link area

Actual result:

Link associated with SI is opened.

Expected result:

Link associated with shortcut should be opened.

Reproduces how often:

Easily reproduced

Brave version (brave://version info)

Brave	1.30.87 Chromium: 94.0.4606.71 (Official Build) (x86_64)
Revision	1d32b169326531e600d836bd395efc1b53d0f6ef-refs/branch-heads/4606@{#1256}
OS	macOS Version 10.14.6 (Build 18G87)

Version/Channel Information:

• Can you reproduce this issue with the current release? Yes
• Can you reproduce this issue with the beta channel? Yes
• Can you reproduce this issue with the nightly channel? Yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields? No
• Does the issue resolve itself when disabling Brave Rewards? No
• Is the issue reproducible on the latest version of Chrome? No

Miscellaneous Information:

Related to #16620

Initial report on Reddit: https://www.reddit.com/r/brave_browser/comments/q1d115/virus_shorcuts_in_the_dashboard_send_me_to_a/