fix: remove receiving EOF from backend after cancel since according t…

…o protocol the server closes the connection once cancel is sent (connection reset exception is always thrown) (#1641)

quote "The server will process this [cancel] request and then close the connection. For security reasons, no direct reply is made to the cancel request message." https://www.postgresql.org/docs/current/protocol-flow.html

pgjdbc/src/main/java/org/postgresql/core/QueryExecutorBase.java

@@ -185,7 +185,6 @@ public void sendQueryCancel() throws SQLException {
       cancelStream.sendInteger4(cancelPid);
       cancelStream.sendInteger4(cancelKey);
       cancelStream.flush();
-      cancelStream.receiveEOF();
     } catch (IOException e) {
       // Safe to ignore.
       LOGGER.log(Level.FINEST, "Ignoring exception on cancel request:", e);

pgjdbc/src/test/java/org/postgresql/test/jdbc2/StatementTest.java

@@ -902,7 +902,7 @@ public Void call() throws Exception {
     }
   }
 
-  @Test(timeout = 20000)
+  @Test(timeout = 2000)
   public void testFastCloses() throws SQLException {
     ExecutorService executor = Executors.newSingleThreadExecutor();
     con.createStatement().execute("SET SESSION client_min_messages = 'NOTICE'");