Auto-Contribute pref hover state should apply to whole label, not just toggle widget

[stephendonner]

Description

Auto-Contribute pref hover state should apply to whole label, not just toggle widget

Steps to Reproduce

1. install 1.38.6
2. launch Brave
3. open brave://settings/rewards
4. hover over the Auto-Contribute label (nothing happens)
5. hover over its on/off toggle widget

Actual result:

Highlight only is applied to the toggle widget

Expected result:

Highlight should apply to the whole pref "line," including its label

Reproduces how often:

100%

Brave version (brave://version info)

Brave	1.38.9 Chromium: 99.0.4844.45 (Official Build) nightly (x86_64)
Revision	edbc0b8343c7b10fddb0e1b4efb280b0f6e38cab-refs/branch-heads/4844@{#788}
OS	macOS Version 11.6.3 (Build 20G415)

cc @GeetaSarvadnya

[zenparsing]

If we need to add descriptive text we can use the same text that appears on the Rewards settings page.