Adding a contract address auto-populates previously added custom token details

[srirambv]

Description

Adding a contract address auto-populates previously added custom token details

Steps to Reproduce

1. Add a custom token for visible asset on Ropsten
2. Close the custom visible asset dialog
3. Copy a different token contract address to clipboard
4. Add custom token and paste in the contract address from previous step, auto-populates the data for the first token added in step 1
5. Copy wallet address and paste it in the contract address, auto-populates the previous token details from step 4

Note: closing the dialog after it auto-populates and trying to add again doesn't auto-populate it

Actual result:

Custom.Token.Auto-Populate.mp4

Expected result:

Should only auto-populate if the token is already in the visible list but not enabled

Reproduces how often:

Easy

Brave version (brave://version info)

Brave	1.36.106 Chromium: 99.0.4844.45 (Official Build) (64-bit)
Revision	edbc0b8343c7b10fddb0e1b4efb280b0f6e38cab-refs/branch-heads/4844@{#788}
OS	Linux

Version/Channel Information:

• Can you reproduce this issue with the current release? Yes
• 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? NA
• Does the issue resolve itself when disabling Brave Rewards? NA
• Is the issue reproducible on the latest version of Chrome? NA

Miscellaneous Information:

cc: @Douglashdaniel @josheleonard

[Uni-verse]

Verified using

Brave	1.38.90 Chromium: 100.0.4896.79 (Official Build) beta (x86_64) 
Revision	8fb749dcab8700c24213791969e59deb72fee36f-refs/branch-heads/4896@{#1015}
OS	macOS Version 12.3.1 (Build 21E258)

• Adding a contract address does not auto-populate fields with previously added token details