feat: share the same user storage mock instance in tests

[mathieuartu]

Description

This PR ensures we share the same UserStorageMockttpController instance for every user storage endpoint.

Related issues

Fixes:

Manual testing steps

1. Start E2E tests
2. Make sure they pass

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.

[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 [aaee978]

• builds: chrome, firefox
• builds (beta): chrome
• builds (flask): chrome, firefox
• builds (MMI): chrome, firefox
• builds (test): chrome, firefox
• builds (test-flask): chrome, firefox
• build viz: Build System
• mv3: Background Module Init Stats
• mv3: UI Init Stats
• mv3: Module Load Stats
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• code coverage: Report
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

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

Page Load Metrics (2016 ± 50 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	1875	2235	2024	97	47
		domContentLoaded	1847	2181	1981	96	46
		load	1867	2244	2016	105	50
		domInteractive	23	110	59	24	11
		backgroundConnect	9	110	33	28	13
		firstReactRender	58	268	120	47	23
		getState	5	64	19	19	9
		initialActions	0	0	0	0	0
		loadScripts	1313	1635	1456	84	40
		setupStore	11	69	29	23	11
		uiStartup	2086	2560	2258	132	64

Bundle size diffs

• background: 0 Bytes (0.00%)
• ui: 0 Bytes (0.00%)
• common: 0 Bytes (0.00%)

[matteoscurati]

LGTM

[metamaskbot]

Builds ready [7db7aed]

• builds: chrome, firefox
• builds (beta): chrome
• builds (flask): chrome, firefox
• builds (MMI): chrome, firefox
• builds (test): chrome, firefox
• builds (test-flask): chrome, firefox
• build viz: Build System
• mv3: Background Module Init Stats
• mv3: UI Init Stats
• mv3: Module Load Stats
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• code coverage: Report
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

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

Page Load Metrics (2161 ± 152 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	1833	2929	2172	315	151
		domContentLoaded	1787	2919	2136	315	151
		load	1832	2927	2161	316	152
		domInteractive	23	107	54	22	11
		backgroundConnect	9	65	24	15	7
		firstReactRender	84	159	108	16	8
		getState	6	66	30	24	12
		initialActions	0	1	0	0	0
		loadScripts	1326	2358	1626	291	140
		setupStore	11	92	34	26	13
		uiStartup	2042	3184	2403	332	160

Bundle size diffs

• background: 0 Bytes (0.00%)
• ui: 0 Bytes (0.00%)
• common: 0 Bytes (0.00%)