fix: legend defaultProps usage for R19 (recharts#4589)

2.x: Fix issues with React 19 (recharts#4573)

recharts#4542 was incomplete with
regards to `defaultProps`. This PR ensures the test suite is green in
React 19 as well as well as fixing all new warnings introduced in React
19.

---------

Co-authored-by: Coltin Kifer <[email protected]>

2.12.7

2.12.6

2.12.5

2.12.4

2.12.3

2.12.2

2.12.1

2.12.0