[docs] Fix always refresh page when icons search

[pppp606]

• https://github.com/mui/material-ui/issues/34169
• Occurs when non-English
• Change router.pathname to window.location.pathname
  • router.pathname does not include the locale path
• Deleted TODO comment as it is no longer needed.

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• [x] I have followed (at least) the PR section of the contributing guide.

fixed #34169

[mui-bot]

No bundle size changes

Generated by :no_entry_sign: dangerJS against f69c8a2a87c20c68a9bd9d94dca0ddf74f7e6a2c

[siriwatknp]

@ZeeshanTamboli should we close this one?