test: small improvements to test clarity

tests/persistence/test_db_context.py

@@ -6,19 +6,19 @@ from freqtrade.persistence import FtNoDBContext, PairLocks, Trade
 @pytest.mark.parametrize("timeframe", ["", "5m", "1d"])
 def test_FtNoDBContext(timeframe):
     PairLocks.timeframe = ""
-    assert Trade.use_db is True
-    assert PairLocks.use_db is True
+    assert Trade.use_db
+    assert PairLocks.use_db
     assert PairLocks.timeframe == ""
 
     with FtNoDBContext(timeframe):
-        assert Trade.use_db is False
-        assert PairLocks.use_db is False
+        assert not Trade.use_db
+        assert not PairLocks.use_db
         assert PairLocks.timeframe == timeframe
 
     with FtNoDBContext():
-        assert Trade.use_db is False
-        assert PairLocks.use_db is False
+        assert not Trade.use_db
+        assert not PairLocks.use_db
         assert PairLocks.timeframe == ""
 
-    assert Trade.use_db is True
-    assert PairLocks.use_db is True
+    assert Trade.use_db
+    assert PairLocks.use_db