"Start video call" button should be "Start call" on Brave Talk widget

Description

Start video call button should be Start call on Brave Talk widget

Steps to Reproduce

1. new nightly profile
2. launch Brave
3. open a new-tab page
4. click on Customize on the lower right
5. click on Cards
6. click on the + Add button for Brave Talk
7. close the dialog by clicking on the X
8. under Brave Talk, look at the button text

Actual result:

Left: talk.brave.software and, Right: Brave Talk new-tab widget

Start call and Start video call

Expected result:

Button text should read Start call.

Reproduces how often:

100%

Brave version (brave://version info)

Brave	1.29.39 Chromium: 92.0.4515.115 (Official Build) nightly (x86_64)
Revision	48cb2f4029b84b003719740a6cf9ca73f374a857-refs/branch-heads/4515_105@{#4}
OS	macOS Version 11.5.1 (Build 20G80)

Note also: this will require its card image asset to be updated again, if we choose to do so:

[Zulkarnine1]

I’m sorry, but I don’t think I’ll be available. I hope someone else can fix it.

[Zulkarnine1]

Hi, I would like to start working on this issue.