perf: enable tcpNoDelay by default

In [pgjdbc#2341](pgjdbc#2341) the option to
configure tcpNoDelay was added, with a default value of false.

The previous value of this setting was true, as set in
PGStream.changeSocket(Socket) with the following code:
```
    // Submitted by Jason Venner <jason@idiom.com>. Disable Nagle
    // as we are selective about flushing output only when we
    // really need to.
    connection.setTcpNoDelay(true);
```

`changeSocket()` is called from the `PGStream` constructor, which is
called in `ConnectionFactoryImpl`, and then later we overwrite the value
with the one from the properties.

We had a performance issue when upgrading from 42.2.24 to 42.3.3, and we suspected the
issue in 42.3.2 and confirmed that by passing the property `tcpNoDelay=true` to the driver,
the performance issue was fixed.

docs/documentation/head/connect.md

@@ -340,7 +340,7 @@ Connection conn = DriverManager.getConnection(url);
 
 * **tcpNoDelay** = boolean
 
-  Enable or disable TCP nodelay. The default is `false`.
+  Enable or disable TCP nodelay. The default is `true`.
 
 * **unknownLength** = int
 

pgjdbc/src/main/java/org/postgresql/PGProperty.java

@@ -705,8 +705,8 @@ public enum PGProperty {
 
   TCP_NO_DELAY(
       "tcpNoDelay",
-      "false",
-      "Enable or disable TCP no delay. The default is (@code false}."
+      "true",
+      "Enable or disable TCP no delay. The default is (@code true}."
   ),
   /**
    * Specifies the length to return for types of unknown length.

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

@@ -113,7 +113,7 @@ public PGStream(PGStream pgStream, int timeout ) throws IOException {
     int receiveBufferSize = 1024;
     int soTimeout = 0;
     boolean keepAlive = false;
-    boolean tcpNoDelay = false;
+    boolean tcpNoDelay = true;
 
     /*
     Get the existing values before closing the stream