Bump version to 1.11.11-SNAPSHOT. #1710

Job	Run time
build (mssql-plugin)	1h 19m 9s
build (mysql-plugin)	1h 10m 33s
build (cloudsql-mysql-plugin)	1h 14m 43s
build (postgresql-plugin)	32m 0s
build (cloudsql-postgresql-plugin)	6m 19s
build (oracle-plugin)	12m 58s
	4h 35m 42s

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