perf: enable tcpNoDelay by default

[obourgain]

In #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.

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• Does this break existing behaviour? If so please explain.
  no breaking change
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