set kDesktopSharingHubEnabled to false

[rebron]

Description

The sharing hub feature in recent Chrome needs additional consideration. For the time being, set kDesktopSharingHubEnabled to false until users are able to customize the Share link to of providers.

We can keep kDesktopSharingHubEnabled set to true in Beta and Nightly channels as we test this implementation.

Steps to Reproduce

1. Use latest with RC, beta or nightly with latest Chromium 98.
2. brave://flags/#sharing-hub-desktop-omnibox Should be default and in this case will be default enabled.
3. Notice the sharing hub icon and functionality in url bar when visiting any web page (not the new tab page or any internal page).

Actual result:

Expected result:

Same as in 1.34.x with individual icons for QR code, sending of device, and no sharing icon in the url bar.

Reproduces how often:

Easily.

Brave version (brave://version info)

1.35.96 and higher

Version/Channel Information:

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

Miscellaneous Information:

[stephendonner]

Verified PASSED using

Brave	1.35.98 Chromium: 98.0.4758.74 (Official Build) (x86_64)
Revision	d0fe1ec4df090cd3eb02b591228505e12ea476e9-refs/branch-heads/4758@{#935}
OS	macOS Version 11.6.1 (Build 20G224)

Confirmed:

• pref is set to false via brave://prefs-internals
• no share icon/UI shows up in the URL bar
• even re-enabling the hub via brave://flags doesn't bring it back (probably needs a specific pref change)

example	example