Add release note for 1.31.0 #11697

Job	Run time
lint	13m 25s
build-ubicloud-standard-8-jdk-21-snapshot-blockhound	24m 58s
flaky-tests	6m 51s
build-macos-12-jdk-21	1h 11m 9s
site	8m 31s
build-windows-latest-jdk-21	1h 10m 34s
build-ubicloud-standard-8-jdk-8	15m 21s
build-ubicloud-standard-8-jdk-11	17m 40s
build-ubicloud-standard-8-jdk-17-leak	13m 58s
build-ubicloud-standard-8-jdk-17-min-java-11	19m 49s
build-ubicloud-standard-8-jdk-17-min-java-17-coverage	22m 23s
	4h 44m 39s

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