Make Savepoint rollbacks mark the connection dirty (#2149)

Addresses https://github.com/brettwooldridge/HikariCP/issues/2142

src/main/java/com/zaxxer/hikari/pool/ProxyConnection.java

@@ -392,7 +392,7 @@ public abstract class ProxyConnection implements Connection
    public void rollback(Savepoint savepoint) throws SQLException
    {
       delegate.rollback(savepoint);
-      isCommitStateDirty = false;
+      isCommitStateDirty = true;
    }
 
    /** {@inheritDoc} */

src/test/java/com/zaxxer/hikari/pool/ConnectionStateTest.java

@@ -160,7 +160,7 @@ public class ConnectionStateTest
             assertTrue(TestElf.getConnectionCommitDirtyState(connection));
 
             connection.rollback(null);
-            assertFalse(TestElf.getConnectionCommitDirtyState(connection));
+            assertTrue(TestElf.getConnectionCommitDirtyState(connection));
 
             resultSet.updateRow();
             assertTrue(TestElf.getConnectionCommitDirtyState(connection));