[code-infra] Regression tests improvements

[Janpot]

• Remove route discovery through reading links, just pass it through with javascript and page.evaluate.
• Don't await page.waitForFunction(() => window.muiFixture.isReady()); for every navigation, just do it once for all.
• Don't move mouse in every test, we're not clicking links anymore to navigate between cases
• Don't do emulate media in every test, just once for all should be fine
• Do image loading in a single evaluation to avoid back and forth in the CDP multiple times
• Don't use #dev, we don't need the links to be in the page for discovering tests. no need to render hundreds of links

[mui-bot]

Deploy preview: https://deploy-preview-20441--material-ui-x.netlify.app/

Bundle size report

Bundle	Parsed size	Gzip size
@mui/x-data-grid	0B(0.00%)	0B(0.00%)
@mui/x-data-grid-pro	0B(0.00%)	0B(0.00%)
@mui/x-data-grid-premium	0B(0.00%)	0B(0.00%)
@mui/x-charts	0B(0.00%)	0B(0.00%)
@mui/x-charts-pro	0B(0.00%)	0B(0.00%)
@mui/x-charts-premium	0B(0.00%)	0B(0.00%)
@mui/x-date-pickers	0B(0.00%)	0B(0.00%)
@mui/x-date-pickers-pro	0B(0.00%)	0B(0.00%)
@mui/x-tree-view	0B(0.00%)	0B(0.00%)
@mui/x-tree-view-pro	0B(0.00%)	0B(0.00%)

Details of bundle changes

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