[compiler] Remove playground postinstall script #540

Job	Run time
Discover yarn workspaces	10s
Jest babel-plugin-react-compiler	1m 51s
Lint babel-plugin-react-compiler	1m 6s
Run prettier	1m 21s
Test make-read-only-util	1m 13s
Test snap	1m 22s
Test react-compiler-healthcheck	1m 21s
Test babel-plugin-react-compiler	1m 39s
Test eslint-plugin-react-compiler	1m 30s
Test react-compiler-runtime	1m 12s
	12m 45s

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