fix: Inputting a nonce value messes up the nonce counter setting a totally different number

[blackdevelopa]

Description

Observed that inputed nonce value isn't stored as number and this messes the nonce counter.

Related issues

Fixes: #6482

Manual testing steps

1. Enable Nonce Edit in Advanced Settings
2. Go to test-dapp
3. Initiate a transaction
4. Click to edit nonce
5. Adjust the nonce by manually
6. Save and submit transaction
7. See nonce value submitted

Screenshots/Recordings

Before

http://recordit.co/fh6KDG0R9g

After

http://recordit.co/xwxPU8NjeZ

Pre-merge author checklist

• I’ve followed MetaMask Coding Standards.
• I've clearly explained what problem this PR is solving and how it is solved.
• I've linked related issues
• I've included manual testing steps
• I've included screenshots/recordings if applicable
• I’ve included tests if applicable
• I’ve documented my code using JSDoc format if applicable
• I’ve applied the right labels on the PR (see labeling guidelines). Not required for external contributors.
• 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: 4 lines in your changes are missing coverage. Please review.

Comparison is base (266154a) 40.42% compared to head (0c367d4) 40.62%.
Report is 28 commits behind head on main.

Files	Patch %	Lines
app/components/UI/CustomNonceModal/index.js	0.00%	2 Missing ⚠️
app/components/Views/SendFlow/Confirm/index.js	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8468      +/-   ##
==========================================
+ Coverage   40.42%   40.62%   +0.19%     
==========================================
  Files        1239     1239              
  Lines       29976    29992      +16     
  Branches     2869     2870       +1     
==========================================
+ Hits        12117    12183      +66     
+ Misses      17168    17111      -57     
- Partials      691      698       +7     

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

[sonarcloud]

Quality Gate passed

Kudos, no new issues were introduced!

0 New issues
0 Security Hotspots
20.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[github-actions]

E2E test started on Bitrise: https://app.bitrise.io/app/be69d4368ee7e86d/pipelines/7ab10644-7a0f-48e7-bf42-880ae32fbb38
You can also kick off another Bitrise E2E smoke test by removing and re-applying the (Run Smoke E2E) label