Monthly auto-contribution limit dropdown is disabled in brave://settings/rewards even when Rewards is enabled

[GeetaSarvadnya]

Description

Found while testing #18158
Monthly auto-contribution limit dropdown is disabled in brave://settings/rewards even when Rewards is enabled

Steps to Reproduce

1. Clean profile 1.33.x
2. Open a tab and navigate to brave://settings/rewards
3. Don't enable rewards
4. Open 2nd tab and enter brave://rewrads and enable rewards in this tab
5. Open 1st tab and observe Monthly auto-contribution limit dropdown is disabled in brave://settings/rewards

Note: Refresh/reload page fixes the issue.

Actual result:

Expected result:

Monthly auto-contribution limit dropdown should be enabled in brave://settings/rewards

Reproduces how often:

Easy

Brave version (brave://version info)

Brave	1.33.83 Chromium: 96.0.4664.45 (Official Build) beta (64-bit)
Revision	76e4c1bb2ab4671b8beba3444e61c0f17584b2fc-refs/branch-heads/4664@{#947}
OS	Windows 10 Version 21H1 (Build 19043.1348)

## Version/Channel Information:

• Can you reproduce this issue with the current release? NA
• 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? NA
• Does the issue resolve itself when disabling Brave Rewards? NA
• Is the issue reproducible on the latest version of Chrome? NA

Miscellaneous Information:

cc: @brave/legacy_qa @emerick @Miyayes

[GeetaSarvadnya]

Verification passed on

Brave | 1.33.94 Chromium: 96.0.4664.45 (Official Build) beta (64-bit)
-- | --
Revision | 76e4c1bb2ab4671b8beba3444e61c0f17584b2fc-refs/branch-heads/4664@{#947}
OS | Windows 10 Version 21H2 (Build 19044.1387)

• Verified the STR from the description and ensured Monthly auto-contribution limit is not disabled, it's showing up the Default value in the dropdown
• Restart the browser and ensure Monthly auto-contribution limit is not disabled
• Open brave://settings/rewards in a new windows and ensured Monthly auto-contribution limit is not disabled