chore: remove MM_CHAIN_PERMISSIONS flag

[wenfix]

Description

Enables the behaviour gated by MM_CHAIN_PERMISSIONS feature flag to be available by default. Dapps requesting network changes via wallet_addEthereumChain or wallet_switchEthereumChain will prompt the user to add permission to access the specified chain IDs and, if granted, subsequent wallet_switchEthereumChain requests made to that chainId will not require user confirmation.

Related issues

Fixes: https://github.com/MetaMask/MetaMask-planning/issues/5026

Manual testing steps

1. Navigate to a dapp and request a network switch to a chain ID not yet permitted.
2. Observe that a permission prompt appears asking to grant access to the requested network.
3. Approve the permission and verify that the network switch occurs successfully.
4. Repeat the network switch request and confirm that no prompt appears, indicating the permission is saved.
5. Attempt to switch to a different, unpermitted network and deny the permission. Verify that the network does not switch.

Screenshots/Recordings

Before

After

Pre-merge author checklist

• I’ve followed MetaMask Contributor Docs and MetaMask Mobile 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.

[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.

[github-actions]

Bitrise

✅✅✅ pr_smoke_e2e_pipeline passed on Bitrise! ✅✅✅

Commit hash: 02a4d35
Build link: https://app.bitrise.io/app/be69d4368ee7e86d/pipelines/21f9b205-cb05-46df-b239-53488041e0e7

Note

• You can kick off another pr_smoke_e2e_pipeline on Bitrise by removing and re-applying the Run Smoke E2E label on the pull request

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

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

See analysis details on SonarQube Cloud

[adonesky1]

Why is the optional chaining required now?

[ffmcgee725]

➕

[wenfix]

ethChainIds can be either an array or undefined and I think previously the flag was preventing that condition to be reached when it was undefined. After the change, tests broke when entering that condition.