center the number of trackers on the shields panel - follow up to 21601

[LaurenWags]

Description

Follow up to #21601

When you hover over the trackers/ads blocked (and likely the HTTPS count and blocked scripts count), the number is not centered in the hover area. See screenshots below.

Steps to Reproduce

1. Visit a page with 99+ trackers/ads blocked (ex. https://d3ward.github.io/toolz/adblock.html)
2. Open shields
3. View Advanced if it's not shown
4. Hover over the 99+ on the same line as "Trackers & ads blocked"

Actual result:

99+ looks like it's right aligned, not centered in the hover area:

Dark theme	Light theme

Expected result:

99+ to be centered in hover area

Reproduces how often:

easily

Brave version (brave://version info)

Brave	1.38.80 Chromium: 100.0.4896.79 (Official Build) beta (x86_64)
Revision	8fb749dcab8700c24213791969e59deb72fee36f-refs/branch-heads/4896@{#1015}
OS	macOS Version 12.3.1 (Build 21E258)

Version/Channel Information:

• Can you reproduce this issue with the current release? 1.37.x n/a
• Can you reproduce this issue with the beta channel? 1.38.x yes
• Can you reproduce this issue with the nightly channel? 1.39.x yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
• Does the issue resolve itself when disabling Brave Rewards?
• Is the issue reproducible on the latest version of Chrome?

Miscellaneous Information:

[rebron]

cc: @aguscruiz @nullhook

[rebron]

Closing as wontfix. We do want this right aligned.