fix: should not reset market data after switch network

[salimtb]

Explanation

This Pull Request addresses an issue where market data would unnecessarily reset following a network switch. The purpose of this update is to ensure that market data remains intact and continues to function as expected after a network change, preventing potential data loss or disruptions in user experience

References

Changelog

@metamask/assets-controller

• CHANGED: Prevent market data reset after a network switch.

Checklist

• [ ] I've updated the test suite for new or updated code as appropriate
• [ ] I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• [ ] I've highlighted breaking changes using the "BREAKING" category above as appropriate
• [ ] I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes

[salimtb]

Should we also write a test: should append marketData for each chain? Or, is that not something included in this PR?

good idea , i'll add this test