chore: update version to 999-SNAPSHOT #6707

Job	Run time
sample_operators_tests (sample-operators/webpage)	1m 5s
sample_operators_tests (sample-operators/mysql-schema)	1m 8s
sample_operators_tests (sample-operators/tomcat-operator)	1m 7s
sample_operators_tests (sample-operators/leader-election)	1m 5s
sample_operators_tests (sample-operators/metrics-processing)	1m 1s
	5m 26s

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