cherry-pick 29968: fix: handle null STX status containing pre-enabled state

[httpJunkie]

cherry-picks #29968

Description

Only remaining QA issue for feature: [EXT] STX Banner Alert & STX x Default Migration

Update migration to treat null preference value as an existing enabled state, preventing unneeded banner display for v12.6.0-12.7.2 migrations.

The update removes the null check in the migration's transformState function (near line 46 of 135.ts)

  if (
    currentOptInStatus === undefined ||
    currentOptInStatus === null ||  // remove this line
    (currentOptInStatus === false && !hasExistingSmartTransactions(state))
  ) {

And let the condition fall through to the else block. This will ensure that smartTransactionsMigrationApplied: false and ensure that we don't see a banner on Transaction Confirmation.

Related issues

Fixes: #29970

Description
Migration fails when the origin extension is version 12.7.x (tested 1 and 2)
In this cases, the alert banner is displayed in the confirmation screen (e.g: send and swaps) when the parameter STX in settings was enabled in the older extension.

Expected behavior
The behaviour should be:
extension 12.11.0 < with STX activated -> update to 12.11.0 and no banner is displayed in the confirmation screen

Manual testing steps for fix

1. Migrate from any version 12.6.* to 12.7.* to 12.10.1 (or 12.11.0 depending)
2. Ensure that STX is ON in the old version (before migrating to the newer version)
3. After migration try to Swap or Send on Ethereum Mainnet & Sepolia and ensure there is no STX Banner Alert shown

Screenshots/Recordings

For users with STX ON before and after Migration:

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.

[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.

[metamaskbot]

Builds ready [2bcd14b]

• builds: chrome, firefox
• builds (flask): chrome, firefox
• builds (MMI): chrome
• builds (test): chrome, firefox
• builds (test-flask): chrome, firefox
• build viz: Build System
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4, 5, 6, 7
  • common: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13
  • ui: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13
  • content-script: 0
  • offscreen: 0

Page Load Metrics (2027 ± 133 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	307	2863	1768	664	319
		domContentLoaded	1644	2847	1985	281	135
		load	1667	2867	2027	277	133
		domInteractive	28	166	62	38	18
		backgroundConnect	16	77	40	19	9
		firstReactRender	18	100	60	27	13
		getState	7	97	24	23	11
		initialActions	0	1	0	0	0
		loadScripts	1200	2183	1510	237	114
		setupStore	6	19	10	3	1
		uiStartup	1919	3342	2358	356	171