[ci] Try to parallelize devtools builds

[poteto]

Building DevTools is currently the long pole for the runtime CI job. Let's see if we can get the overall runtime for runtime build and test down by speeding this one step up.

Stack created with Sapling. Best reviewed with ReviewStack.

• [ci] Remove build_devtools_and_process_artifacts as a dependency to run_devtools_e2e_tests #32267
• -> [ci] Try to parallelize devtools builds #32266

[react-sizebot]

Comparing: bb9a24d9fc5faa57a85750cd3bb94546baa405ac...ab21bf7c2a037c52cf2a33be0f8032d893fc3a05

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	=	515.10 kB	515.10 kB	=	91.81 kB	91.81 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	=	558.79 kB	558.79 kB	=	99.12 kB	99.12 kB
facebook-www/ReactDOM-prod.classic.js	=	597.07 kB	597.07 kB	=	104.95 kB	104.95 kB
facebook-www/ReactDOM-prod.modern.js	=	587.50 kB	587.50 kB	=	103.41 kB	103.41 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against ec50f28