data: Swap default for 'disable-extension-version-check' setting

Nowadays, the user interface has mostly stabilized with most changes
happening under the hood. As a result, extensions written for previous
versions of GNOME Shell are very much expected to keep working on
updates, if it wasn't for the version check that requires a version
bump in the extension metadata. There has been a setting to disable
that check for a while, but it's existence isn't widely known (hence
the common perception that "everything breaks on updates"). While
there is still some risk that an out-of-date extension can be enabled
without error, but fails spectacularly later (where we cannot catch
the exception), it is reasonably small by now when compared to the
~95% of extensions that can be "unbroken", so swap the default value
to disable version checks by default.

https://bugzilla.gnome.org/show_bug.cgi?id=770887