[Backport 2.x] Drafted 2.11 release notes. #2536

Job	Run time
test-and-build (11, ubuntu-latest, ism)	23m 37s
test-and-build (11, ubuntu-latest, non-ism)	16m 43s
test-and-build (11, windows-latest, ism)	6m 30s
test-and-build (11, windows-latest, non-ism)	6m 21s
test-and-build (11, macos-latest, ism)	6m 54s
test-and-build (11, macos-latest, non-ism)	5m 53s
test-and-build (17, ubuntu-latest, ism)	22m 11s
test-and-build (17, ubuntu-latest, non-ism)	15m 10s
test-and-build (17, windows-latest, ism)	4m 22s
test-and-build (17, windows-latest, non-ism)	6m 3s
test-and-build (17, macos-latest, ism)	4m 56s
test-and-build (17, macos-latest, non-ism)	6m 31s
	2h 5m 11s

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