[ci] Only checkout if no cache hit

[poteto]

We don't need to do a checkout for the node_modules cache jobs if there's a cache hit. Saves a few seconds.

Stack created with Sapling. Best reviewed with ReviewStack.

• -> [ci] Only checkout if no cache hit #32856
• Upgrade node.js to 20 LTS #32855

[react-sizebot]

Comparing: 1d6c816...8b38201

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	+0.05%	1.83 kB	1.83 kB
oss-stable/react-dom/cjs/react-dom-client.production.js	=	516.18 kB	516.18 kB	=	91.88 kB	91.88 kB
oss-experimental/react-dom/cjs/react-dom.production.js	=	6.69 kB	6.69 kB	+0.05%	1.83 kB	1.83 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js	=	621.49 kB	621.49 kB	=	110.01 kB	110.01 kB
facebook-www/ReactDOM-prod.classic.js	=	654.79 kB	654.79 kB	=	115.57 kB	115.57 kB
facebook-www/ReactDOM-prod.modern.js	=	645.07 kB	645.07 kB	=	114.04 kB	114.04 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against 8b38201