Monthly Contribution Dropdown in Wallet Panel should retain value

[ryanml]

This should call the functions SaveRecurringDonation and RemoveRecurring. The former should called when a non-0 value is set, and the latter when 0 is set.

Description

Steps to Reproduce

1. Enable Brave Rewards
2. Navigate to a site such as brave.com
3. Bring up the wallet panel.
4. Change monthly contribution amount to '5.0'
5. Close and re-open panel

Actual result:

New value is not returned, is 0.0

Expected result:

Dropdown should be 5.0

Reproduces how often:

Brave version (brave://version info)

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds?

Website problems only:

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

Additional Information

[kjozwiak]

Hope we can land this before 0.58.x moves into beta or this will need to get uplifted 👍

[bbondy]

Reverted due to failing unit tests, re-opening.
brave/brave-core@f77acbe

[GeetaSarvadnya]

Verification passed on

Brave	0.65.93 Chromium: 74.0.3729.131 (Official Build) beta (64-bit)
Revision	518a41c1fa7ce1c8bb5e22346e82e42b4d76a96f-refs/branch-heads/3729@{#954}
OS	Windows 10 OS Build 17134.523

• Verified the test plan from Adds functionality to monthly contribution dropdown (Panel) brave-core#957
• Verified Twitch, YT and websites

Verification passed on

Brave	0.65.97 Chromium: 74.0.3729.131 (Official Build) beta(64-bit)
Revision	518a41c1fa7ce1c8bb5e22346e82e42b4d76a96f-refs/branch-heads/3729@{#954}
OS	Ubuntu 18.04 LTS

• Verified the test plan from Adds functionality to monthly contribution dropdown (Panel) brave-core#957
• Verified Twitch, YT and websites
• Logged Monthly tip value is not trimmed in Rewards Panel #4502

Verified passed with

Brave	0.65.97 Chromium: 74.0.3729.131 (Official Build) beta(64-bit)
Revision	518a41c1fa7ce1c8bb5e22346e82e42b4d76a96f-refs/branch-heads/3729@{#954}
OS	Mac OS X

• Verified test plan from Adds functionality to monthly contribution dropdown (Panel, #3 origin) brave-core#2069