[Fizz] Rename ReactFizzContext to ReactFizzLegacyContext

[sebmarkbage]

#33622 forgot these.

[react-sizebot]

Comparing: 9406162...e2c1955

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.js	=	6.68 kB	6.68 kB	=	1.83 kB	1.83 kB
oss-stable/react-dom/cjs/react-dom-client.production.js	=	530.57 kB	530.57 kB	=	93.67 kB	93.67 kB
oss-experimental/react-dom/cjs/react-dom.production.js	=	6.69 kB	6.69 kB	=	1.83 kB	1.83 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js	=	651.66 kB	651.66 kB	=	114.79 kB	114.78 kB
facebook-www/ReactDOM-prod.classic.js	=	674.81 kB	674.81 kB	=	118.78 kB	118.78 kB
facebook-www/ReactDOM-prod.modern.js	=	665.30 kB	665.30 kB	=	117.20 kB	117.19 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against e2c1955

[kassens]

Thanks, sorry I missed these.