Remove DNS.Resolvers IPNS config property if user disables DOH

[cypt4]

Dns override doesn't falls back when DOH removed.
Config still contains DNS.Resolvers property after user switches to system DNS.

[kjozwiak]

The above will require 1.43.81 or higher for 1.43.x verification. @StephenBass believe this wasn't working so you created a follow up via #24900 when running through the verification's via brave/brave-core#14631 (comment) before we uplift into 1.43.x. Should this be labelled as QA/No in that case?

[kjozwiak]

@cypt4 mind taking a look? Is this something we should fix? Seems like it's a P2 so assuming we want to get #24900 fixed.

[stephendonner]

The above will require 1.43.81 or higher for 1.43.x verification. @StephenBass believe this wasn't working so you created a follow up via #24900 when running through the verification's via brave/brave-core#14631 (comment) before we uplift into 1.43.x. Should this be labelled as QA/No in that case?

We can QA/No this one, as -- at any rate -- I wasn't able to get it working, with my steps. Pending the outcome/fix of #24900, we can change the label back, if need-be.

[stephendonner]

Verification PASSED using

Brave	1.43.81 Chromium: 104.0.5112.102 (Official Build) (x86_64)
Revision	8e5396254975ef939f2ef7d0bd334e48a052b536-refs/branch-heads/5112@{#1478}
OS	macOS Version 11.6.8 (Build 20G730)

Steps:

1. installed 1.43.81
2. launched Brave
3. loaded brave://ipfs-internals/
4. clicked on Install and start
5. chose NextDNS as a DoH provider in brave://settings/security
6. shut down Brave
7. opened {profile_folder}/brave_ipfs/config in a text editor
8. confirmed there's a DNS entry with Resolvers: and NextDNS is listed
9. relaunch Brave
10. set DNS back to With your current service provider
11. loaded ipns://ipfs.io
12. clicked on Use a local Brave IPFS node
13. waited for ipns://ipfs.tech/ to finish loading
14. shut down Brave
15. opened {profile_folder}/brave_ipfs/config in a text editor
16. searched for DNS / Resolver

Confirmed the DNS Resolver section was removed

example	example	example	example	example	example	example

[MadhaviSeelam]

Verification PASSED using

Brave | 1.43.89 Chromium: 105.0.5195.102 (Official Build) (64-bit)
-- | --
Revision | 4c16f5ffcc2da70ee2600d5db77bed423ac03a5a-refs/branch-heads/5195_55@{#4}
OS | Windows 11 Version 21H2 (Build 22000.856)

Steps:

1. installed 1.43.89
2. launched Brave
3. loaded brave://ipfs-internals/
4. clicked on Install and start
5. chose NextDNS as a DoH provider in brave://settings/security
6. shut down Brave
7. opened {profile_folder}/brave_ipfs/config in a text editor
8. confirmed there's a DNS entry with Resolvers: and NextDNS is listed
9. relaunch Brave
10. set DNS back to With your current service provider
11. loaded ipns://ipfs.io
12. clicked on Use a local Brave IPFS node
13. waited for ipns://ipfs.tech/ to finish loading
14. shut down Brave
15. opened {profile_folder}/brave_ipfs/config in a text editor
16. searched for DNS / Resolver

Confirmed the DNS Resolver section was removed

step 4	step5	step 7-8	step10	step 11	step12	step 13	step15-16