[Improvement] Improve GravitinoCatalogManager close method

What would you like to be improved?

GravitinoCatalogManager's close method mixes static and volatile variables in a nonstatic method and that may cause issues. Correctly updating a static field from a non-static method can be tricky to get right and could easily lead to bugs if there are multiple threads.

How should we improve?

See if this can be improved to be more thread safe.