fix: Update Beta build configuration (#25430)

## **Description**

The Beta build configuration was stale, which indirectly resulted in
build failures (due to a code fence bug). The beta config should match
the `main` config with respect to feature support.

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## **Related issues**

N/A

## **Manual testing steps**

Run `yarn build --build-type beta --platform='chrome' dist` and see that
it succeeds in creating a build. This is failing on `develop`.

## **Screenshots/Recordings**

N/A

## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I’ve included tests if applicable
- [x] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/LABELING_GUIDELINES.md)).
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.

---------

Co-authored-by: MetaMask Bot <metamaskbot@users.noreply.github.com>

builds.yml

@@ -39,11 +39,18 @@ buildTypes:
   beta:
     features:
       - build-beta
+      - snaps
+      - keyring-snaps
+      - blockaid
     env:
       - INFURA_BETA_PROJECT_ID
       - SEGMENT_BETA_WRITE_KEY
       - INFURA_ENV_KEY_REF: INFURA_BETA_PROJECT_ID
       - SEGMENT_WRITE_KEY_REF: SEGMENT_BETA_WRITE_KEY
+      - ALLOW_LOCAL_SNAPS: false
+      - REQUIRE_SNAPS_ALLOWLIST: true
+      - IFRAME_EXECUTION_ENVIRONMENT_URL: https://execution.metamask.io/iframe/6.4.0/index.html
+      - ACCOUNT_SNAPS_DIRECTORY_URL: https://snaps.metamask.io/account-management
     # Modifies how the version is displayed.
     # eg. instead of 10.25.0 -> 10.25.0-beta.2
     isPrerelease: true