Add sync and object store tests to the Evergreen valgrind task

[sync-by-unito]

As of today, the valgrind Evergreen task is currently running against the core tests. Add the following tests to be included with this task and run against valgrind. Depending on how long these tests take, it may be necessary to wait until EVG-20622 has been implemented and the nightly periodic builds are working properly.

• realm-sync-tests
• realm object store tests without baas
• realm object store tests with baas
• realm object store network tests? (could be a future/later addition)