omxvideocodec: avoid double flush during teardown

In order to save some precious ms in a multiple omx pipeline
configuration, flush should be performed
only once during the element teardown  and after putting the
gst_omx_component_set_state to OMX_StateIdle
, avoiding a slow port creation.
9 jobs for dab_avoid_flush_twice in 15 minutes and 22 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Preparation
passed gst indent #1798110

00:00:18

passed manifest #1798109

00:00:48

 
  Build
passed build clang fedora x86_64 #1798115

00:11:01

passed build fedora x86_64 #1798111

00:09:55

passed build gst-omx zynq fedora x86_64 #1798116

00:06:04

passed build nodebug fedora x86_64 #1798112

00:09:04

passed build static fedora x86_64 #1798113

00:13:00

passed build static nodebug fedora x86_64 #1798114

00:07:14

 
  Integrate
passed documentation #1798117

00:04:29