Revert "Support writing to this.refs from userspace"

[kassens]

Reverts #28867

It broke some tests, reverting until we figure out why to avoid having too much delay in the sync.

[react-sizebot]

Comparing: 33a3244...625cf29

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.min.js	=	168.91 kB	168.92 kB	+0.01%	52.94 kB	52.94 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	=	170.56 kB	170.57 kB	+0.02%	53.43 kB	53.44 kB
facebook-www/ReactDOM-prod.classic.js	=	590.81 kB	590.83 kB	=	103.90 kB	103.91 kB
facebook-www/ReactDOM-prod.modern.js	=	566.62 kB	566.65 kB	=	100.09 kB	100.10 kB
test_utils/ReactAllWarnings.js	Deleted	64.44 kB	0.00 kB	Deleted	16.10 kB	0.00 kB

Significant size changes

Includes any change greater than 0.2%:

Expand to show

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable-semver/react/cjs/react.production.js	+0.34%	35.36 kB	35.48 kB	+0.11%	10.03 kB	10.04 kB
oss-stable/react/cjs/react.production.js	+0.34%	35.39 kB	35.51 kB	+0.11%	10.06 kB	10.07 kB
oss-experimental/react/cjs/react.production.js	+0.32%	37.04 kB	37.16 kB	+0.08%	10.41 kB	10.42 kB
test_utils/ReactAllWarnings.js	Deleted	64.44 kB	0.00 kB	Deleted	16.10 kB	0.00 kB

Generated by 🚫 dangerJS against 625cf29