Fix Race condition in db_sst_test (#8092)

Summary:
Fix race condition in
DBSSTTest.DBWithMaxSpaceAllowedWithBlobFiles where background flush
thread updates delete_blob_file but in test thread Flush() already
completes after getting bg_error and delete_blob_file remains false.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8092

Test Plan: Ran ASAN job few times on CircleCI

Reviewed By: riversand963

Differential Revision: D27275815

Pulled By: akankshamahajan15

fbshipit-source-id: 2939ad1671403881573bbe07c71aa474c5019130

db/db_sst_test.cc

@@ -1088,6 +1088,12 @@ TEST_F(DBSSTTest, DBWithMaxSpaceAllowedWithBlobFiles) {
   ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
       "BuildTable::AfterDeleteFile",
       [&](void* /*arg*/) { delete_blob_file = true; });
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->LoadDependency({
+      {
+          "BuildTable::AfterDeleteFile",
+          "DBSSTTest::DBWithMaxSpaceAllowedWithBlobFiles:1",
+      },
+  });
 
   ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->EnableProcessing();
 
@@ -1095,6 +1101,8 @@ TEST_F(DBSSTTest, DBWithMaxSpaceAllowedWithBlobFiles) {
   // This flush will fail
   ASSERT_NOK(Flush());
   ASSERT_TRUE(max_allowed_space_reached);
+
+  TEST_SYNC_POINT("DBSSTTest::DBWithMaxSpaceAllowedWithBlobFiles:1");
   ASSERT_TRUE(delete_blob_file);
   ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->DisableProcessing();
 }