Bump version to 2.10.9 (#18033) #6

Job	Run time
Ensure Go modules synchronicity	37s
Build, test & lint UI code	2m 6s
Build & cache Go code	3m 11s
Lint Go code	5m 12s
Check changes to generated code	8m 30s
Run unit tests with -race for Go packages	7m 38s
Run end-to-end tests (v1.28.2)	45m 19s
Run unit tests for Go packages	4m 2s
Run end-to-end tests (v1.27.6)	44m 0s
Run end-to-end tests (v1.26.9)	50m 56s
Run end-to-end tests (v1.25.14)	45m 26s
Process & analyze test artifacts	28s
	3h 37m 25s

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