test: decproxy: Don't use pad block when extracting event
test: decproxy: Don't use pad block when extracting event

To hold data before loading a real decoder, extended pad will be
more proper approach.

Change-Id: Ifc93dbe708142004f3eae957814ee172fb27ed7f
Reviewed-on: https://gpro.palm.com/60945
Tested-by: Jeongseok Kim <0c03ab7a1b32f29697716389c3f9549845834271@lge.com>
Reviewed-by: Myoungsun Lee <ef5eccacceb504b4a99b43e8045acc257d388079@lge.com>
Reviewed-by: HoonHee Lee <41497318ef67053f37c2ac0e974a3369f66d66ec@lge.com>
Reviewed-by: Jeongseok Kim <0c03ab7a1b32f29697716389c3f9549845834271@lge.com>

justinjoy/gst-plugins-cool,justinjoy/gst-plugins-cool