Use latest designs for pending transaction panel confirm and reject buttons

[josheleonard]

Description

Steps to Reproduce

1. create a pending transaction
2. observe the confirm and reject buttons

Actual result:

the buttons have a large border radius and have icons

Expected result:

the buttons have a smaller border radius and no icons

Reproduces how often:

Brave version (brave://version info)

Version/Channel Information:

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

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:

[srirambv]

Verification passed on

Brave	1.65.89 Chromium: 123.0.6312.58 (Official Build) beta (64-bit)
Revision	2975bd8d3905ed79de82dd9fa11b6e4019075dd6
OS	Windows 11 Version 23H2 (Build 22631.3296)

• Verified steps from issue description
• Verified Confirm/Reject buttons have a bigger border radius and doesn't have any icons