Add note re: PRs to CONTRIBUTING.md #34885

Job	Run time
browser-integration	1m 38s
coverage	12m 10s
knip	31s
typecheck	41s
format	32s
baselines	10m 9s
package-size	1m 26s
self-check	58s
lint	1m 4s
misc	26s
smoke	50s
Test Node 24 on macos-latest	11m 32s
Test Node 20 on ubuntu-latest	11m 47s
Test Node 18 on ubuntu-latest	13m 3s
Test Node 16 on windows-latest	15m 28s
Test Node 16 on macos-latest	18m 0s
Test Node 18 on windows-latest	15m 56s
Test Node 20 on windows-latest	14m 19s
Test Node 14 on ubuntu-latest	12m 56s
Test Node 22 on windows-latest	13m 18s
Test Node 24 on ubuntu-latest	9m 17s
Test Node 24 on windows-latest	11m 23s
Test Node lts/* on ubuntu-latest with --no-bundle	12m 58s
Test Node 22 on ubuntu-latest	11m 23s
Test Node 14 on windows-latest	16m 22s
Test Node 16 on ubuntu-latest	12m 34s
required	3s
	3h 50m 44s

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