Test 150 clients migrated to `Cache [6]` suite

[Дмитрий Рябов]

Hello Igniters!



I migrated test `IgniteCache150ClientsTest` from `150 Clients` suite to `
Cache [6]`, because `150 Clients` contains only one test class and makes
~6min excess Ignite build.



So, test suites `150 Clients` and `~[Obsolete] 150 Clients` will be deleted
 soon.