Squish: Fix tst_git_local

Change-Id: I6acdaaf81a0b8c2523df4fda4ee7ec044da25678
Reviewed-by: Robert Loehning <robert.loehning@theqtcompany.com>
TextEditor: Make automatic completion timeout configurable

Allow to configure the timeout in the range from 0 to 500ms.

Task-number: QTCREATORBUG-13393
Change-Id: I3e421109db919ab0dd5d63b8cbb9339fce132dbb
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@theqtcompany.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@theqtcompany.com>