Fix link to testnet faucets

[jpuri]

Description

Fix the link to testnet faucets.

Manual testing steps

_1. Start a transaction and go to confirmation page (ensure that you have less that required ETH on the testnet)
_2. Click the buy option, it should load correct faucet page

Related issues

_Fixes: MetaMask/mobile-planning#1255

Pre-merge author checklist

• I’ve followed MetaMask Coding Standards.
• I've clearly explained:
  • What problem this PR is solving.
  • How this problem was solved.
  • How reviewers can test my changes.
• I’ve indicated what issue this PR is linked to: Fixes #???
• I’ve included tests if applicable.
• I’ve documented any added code.
• I’ve applied the right labels on the PR (see labeling guidelines).
• I’ve properly set the pull request status:
  • In case it's not yet "ready for review", I've set it to "draft".
  • In case it's "ready for review", I've changed it from "draft" to "non-draft".

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[codecov-commenter]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (d2623c8) 34.65% compared to head (888febf) 34.65%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7546   +/-   ##
=======================================
  Coverage   34.65%   34.65%           
=======================================
  Files        1023     1023           
  Lines       27338    27346    +8     
  Branches     2242     2242           
=======================================
+ Hits         9473     9478    +5     
- Misses      17367    17370    +3     
  Partials      498      498           

Files	Coverage Δ
app/constants/urls.ts	100.00% <100.00%> (ø)
app/core/AppConstants.ts	80.00% <ø> (ø)
app/util/networks/index.js	75.93% <100.00%> (+0.55%)	⬆️
...pp/components/UI/ApproveTransactionReview/index.js	3.84% <0.00%> (-0.02%)	⬇️
...actionReview/TransactionReviewInformation/index.js	37.16% <0.00%> (-0.34%)	⬇️
app/components/Views/SendFlow/Confirm/index.js	43.79% <0.00%> (-0.17%)	⬇️

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[blackdevelopa]

Looks good to me.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

1 Bug
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

39.1% Coverage
0.0% Duplication

[jpuri]

Bitrise: https://app.bitrise.io/app/be69d4368ee7e86d/pipelines/269de88a-95d8-4835-89e5-73a75aa60148