Since we directly called beginConnection in connectionStartupFailed
we got a stack overflow over time. Instead, only try to connect
every 3 seconds.

Also remove special logic for mixed debugging: They should behave
the same (except maybe where you're breaking inside QQmlDebugServer,
but that's a corner case).

Change-Id: Idf2f55e3d905a01065c123c708b50dbb88388d1f
Reviewed-by: Aurindam Jana <aurindam.jana@nokia.com>