test: [POM] fix change language flaky tests and migrate tests to Page Object Model

[chloeYue]

Description

• Fix change language flaky tests. There are multiple reasons for the flakiness, including taking actions during the loading spinner and excessive misuse of refresh page
• Migrate change language e2e tests to Page Object Model
• Created base pages for advanced settings page and general settings page
• For some special language-related locators, as they are only used in this specific test, I didn't migrate them to POM methods.

Related issues

Fixes:#27904 #28698 #27390

Manual testing steps

Check code readability, make sure tests 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 [8041302]

• 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, 7
  • common: 0, 1, 10, 11, 12, 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 (2153 ± 86 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	408	2450	1987	547	263
		domContentLoaded	1828	2439	2127	179	86
		load	1858	2454	2153	179	86
		domInteractive	29	131	50	23	11
		backgroundConnect	8	80	28	22	10
		firstReactRender	17	96	38	25	12
		getState	27	103	78	22	11
		initialActions	0	1	0	0	0
		loadScripts	1357	1885	1629	154	74
		setupStore	7	54	14	13	6
		uiStartup	2106	2922	2488	202	97

Bundle size diffs

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

[itsyoboieltr]

LGTM!

[seaona]

LGTM!