chore: set next branch version to 999-SNAPSHOT #7406

Job	Run time
sample_operators_tests (sample-operators/leader-election)	4m 9s
sample_operators_tests (sample-operators/tomcat-operator)	4m 10s
sample_operators_tests (sample-operators/mysql-schema)	3m 27s
sample_operators_tests (sample-operators/webpage)	4m 11s
sample_operators_tests (sample-operators/operations)	9m 31s
	25m 28s

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