Deleting a custom RPC URL should remove input field

[tredondo]

Description

At brave://settings/wallet/networks, add a new network (see #19781), then double click it

Steps to Reproduce

1. brave://settings/wallet/networks
2. Add a new network, e.g. BSC
3. Make sure to add all three RPC URLs
4. Click "Submit"
5. Double-click the network
6. Delete the last 2 RPC URLs.
7. Try to Submit

Actual result:

Expected result:

Delete the URLs either with a UX affordance, or by not erroring out if the user has cleared those fields.

Reproduces how often:

Every time

Brave version (brave://version info)

Brave	1.32.113 Chromium: 96.0.4664.45 (Official Build) (64-bit)
Revision	76e4c1bb2ab4671b8beba3444e61c0f17584b2fc-refs/branch-heads/4664@{#947}
OS	Linux

Version/Channel Information:

Version 1.32.113 Chromium: 96.0.4664.45 (Official Build) (64-bit)

Miscellaneous Information:

Adding the BSC mainnet from these settings resulted in a ridiculous BNB balance (trillions).

[LaurenWags]

Verification in progress with

Brave | 1.34.67 Chromium: 97.0.4692.56 (Official Build) beta (x86_64)
-- | --
Revision | 04da6c66398ca50e603cc236a07dc7dfd3bbc750-refs/branch-heads/4692@{#990}
OS | macOS Version 11.6.1 (Build 20G224)

Reproduced the issue using 1.33.106 and STR:

Verified able to remove RPC URLs as per the STR.
Confirmed for both clean and upgraded profiles.

Step 2	Step 7	Success

[srirambv]

Verification passed on

Brave	1.34.77 Chromium: 97.0.4692.56 (Official Build) (64-bit)
Revision	04da6c66398ca50e603cc236a07dc7dfd3bbc750-refs/branch-heads/4692@{#990}
OS	Windows 11 Version Dev (Build 22523.1000)

• Verified deleting a custom RPC URL shows Invalid Address for the input field but still allows to click on Submit button
• Verified deleting RPC URL and clicking on Submit shows confirmation of updating the custom network
• Verified selecting Ok updates the list and removes the URL and updates the network details

Removed URL	Delete Confirmation	Updated Network details

---

Verification passed on

Brave	1.34.77 Chromium: 97.0.4692.56 (Official Build) (64-bit)
Revision	04da6c66398ca50e603cc236a07dc7dfd3bbc750-refs/branch-heads/4692@{#990}
OS	Linux

• Verified deleting a custom RPC URL shows Invalid Address for the input field but still allows to click on Submit button
• Verified deleting RPC URL and clicking on Submit shows confirmation of updating the custom network
• Verified selecting Ok updates the list and removes the URL and updates the network details

Removed URL	Delete Confirmation	Updated Network details