Buy & Swap screen should be closed when an unsupported network is selected

[srirambv]

Description

Buy & Swap screen should be closed when an unsupported network is selected

Steps to reproduce

1. Add a custom network
2. Set network to mainnet
3. Open Buy/Swap screen
4. Select network drop down and select the custom network
5. Buy screen shows Test Faucet message, Swap screen allows to enter values but throws unknown error

Actual result

Custon.Network.mp4

Expected result

Maybe hide the settings return to portfolio when network is changed on the Buy/Swap screen

Issue reproduces how often

Easy

Version/Channel Information:

• Can you reproduce this issue with the current Play Store version? NA
• Can you reproduce this issue with the current Play Store Beta version? Yes
• Can you reproduce this issue with the current Play Store Nightly version? Yes

Device details

• Install type (ARM, x86): ARM
• Device type (Phone, Tablet, Phablet): All
• Android version: All

Brave version

1.36.87 Beta build

Website problems only

• 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

Additional information

cc: @SergeyZhukovsky @jamesmudgett

[srirambv]

Verification passed on the following devices running 1.36.99 x64 Beta build

• Verified when Buy & Swap screens are opened, custom networks are not listed
• Encountered #21039

Oppo Reno 5 (Android 12)	Samsung Tab A (Android 10)
20977.-.ARM.mp4	20977.-.Tab.mp4