Values in brave://rewards are using defaults, not values from publisher_state

[bsclifton]

Description

Likely the same root cause as #2260

If I do an import for Brave Payments (discovered by @LaurenWags with brave/brave-core#736), values like minimum visit time, # visits, allow unverified contributions, etc are imported and put into the publisher_state file

When you visit brave://rewards, it shows the default values that are coming from here:
https://github.com/brave/brave-core/blob/a07948dd2cb553cb7650d879b81f05f6f5bdcb35/components/brave_rewards/resources/ui/storage.ts#L10-L49

Each web_ui page is keeping its store in local storage... but in this case, the code is never initialized with the values from the RewardsService (in C++)

Test plan / Steps to Reproduce

1. Fresh profile
2. Visit brave://rewards and enable rewards
3. Quit Brave
4. Open the Default/publisher_state file in your session directory, using your favorite editor
5. Edit the JSON and change min_pubslisher_duration to 60
6. Re-launch Brave
7. Open Auto-Contribute settings (the gear icon)

Actual result:

UI shows 8 seconds, not 1 minute

Expected result:

UI should respect value from Default/publisher_state (60 seconds / 1 minute)

Reproduces how often:

100%

Brave version (brave://version info)

master brave/brave-core@a07948d

Reproducible on current release:

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

Additional Information

I started to do a fix last nite and verified that this does indeed set the values:
brave/brave-core@16e2ee6

However, it doesn't seem to set all of the values properly. I might have a misspelling for the preference names

[tmancey]

brave/brave-core#992

[LaurenWags]

Verified passed with

Brave	0.57.12 Chromium: 71.0.3578.75 (Official Build) (64-bit)
Revision	06ef00b5279f93f8e0c1e73acedd49d7dcc09767-refs/branch-heads/3578@{#836}
OS	Mac OS X

• Verified STR in description
• Verified the following settings were imported from muon appropriately: Minimum page time before logging a visit, Minimum visits for publisher relevancy, Allow contribution to non-verified sites, Allow contribution to videos

Verified passed with

Brave	0.57.12 Chromium: 71.0.3578.75 (Official Build) (64-bit)
Revision	06ef00b5279f93f8e0c1e73acedd49d7dcc09767-refs/branch-heads/3578@{#836}
OS	Windows 7 x64

• Verified STR in description

Verification passed on

Brave	0.57.17 Chromium: 71.0.3578.80 (Official Build) (64-bit)
Revision	2ac50e7249fbd55e6f517a28131605c9fb9fe897-refs/branch-heads/3578@{#860}
OS	Linux

• Verified steps from description