fix(samples): remove unused code

[brionmario]

Purpose

This pull request makes minor updates to the SignInPage.tsx and SignUpPage.tsx files by removing unused imports to clean up the code.

Code cleanup:

• samples/teamspace-react/src/pages/SignInPage.tsx: Removed the unused Users import from lucide-react.
• samples/teamspace-react/src/pages/SignUpPage.tsx: Removed the unused Users import from lucide-react.

Related Issues

• N/A

Related PRs

• N/A

Checklist

• e2e cypress tests locally verified.
• Manual test round performed and verified.
• UX/UI review done on the final implementation.
• Documentation provided. (Add links if there are any)
• Unit tests provided. (Add links if there are any)
• Integration tests provided. (Add links if there are any)

Security checks

• Followed secure coding standards in http://wso2.com/technical-reports/wso2-secure-engineering-guidelines?
• Ran FindSecurityBugs plugin and verified report?
• Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets?