rtspconnection: Replace Auth header instead of append

gst_rtsp_connection_send() adds the Authorization header to the request.
If this function is being called multiple times with the same request
it will add one more Authorization header every time.

To fix to this issue do not append a new Authorization header on
top of an existing ones. Remove any existing Authorization headers first
and then add the new one.

Fixes gst-plugins-good#425
4 jobs for fix-multiple-auth-headers in 6 minutes and 4 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Preparation
passed gst indent #58593

00:00:33

passed manifest #58592

00:00:22

 
  Build
passed build fedora x86_64 #58594

00:03:13

 
  Full Builds
passed build android arm64 api28 #58595

00:02:17