Add "max_write_buffer_size_to_maintain" to crash test (#7634)

Summary:
Add "max_write_buffer_size_to_maintain" to crash test

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7634

Test Plan: make crash_test -j64

Reviewed By: zhichao-cao

Differential Revision: D24710401

Pulled By: akankshamahajan15

fbshipit-source-id: 89e0412aaa56b2ef5a75603971b82f4b0b494ab7

tools/db_crashtest.py

@@ -137,6 +137,8 @@ default_params = {
     "sync_fault_injection": False,
     "get_property_one_in": 1000000,
     "paranoid_file_checks": lambda: random.choice([0, 1, 1, 1]),
+    "max_write_buffer_size_to_maintain": lambda: random.choice(
+        [0, 1024 * 1024, 2 * 1024 * 1024, 4 * 1024 * 1024, 8 * 1024 * 1024]),
 }
 
 _TEST_DIR_ENV_VAR = 'TEST_TMPDIR'