chore: remove license from root monorepo

[mikesposito]

Explanation

The licenses included in the monorepo root are being deleted, to align with https://github.com/MetaMask/core/

References

N/A

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 communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them