fix: hide amount in simulations for testnets if its opt out

[OGPoyraz]

Description

This PR aims to hide testnet fiat values if user opt out in the settings.

Related issues

• Fixes: Hide amount in simulations for testnets if it's opted out by user #9906

Manual testing steps

1. Change current network to any testnet
2. Go to setting, turn on "Show conversion on test networks"
3. Try simple send - see fiat values displayed in simulations
4. Go to setting, turn off "Show conversion on test networks"
5. Try simple send - see no fiat values displayed in simulations
6. Change current network to mainnet or any other network which is not testnet
7. Try simple send - see fiat values displayed in simulations

Screenshots/Recordings

Before

After

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Extension Coding Standards.
• I've completed the PR template to the best of my ability
• 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.

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.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
90.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud