validate: blacklist rtsp H265 tests

The version of libav used on the CI crashes in various ways.
Hopefully these issues will go away when we upgrade the image
to Fedora 30, as these don't occur on my machine.
13 jobs for master in 106 minutes and 28 seconds (queued for 1 minute and 7 seconds)
Status Job ID Name Coverage
  Preparation
passed #483667
manifest

00:00:35

 
  Build
passed #483673
build cerbero android universal

00:15:56

passed #483674
build cerbero cross win32

00:10:44

passed #483675
build cerbero cross win64

00:08:13

passed #483672
build cerbero fedora x86_64

00:06:56

manual #483677
gst-ios-12.2 allowed to fail manual
build cerbero ios universal
passed #483676
gst-macos-10.14
build cerbero macos x86_64

00:08:35

passed #483668
build fedora x86_64

00:06:55

passed #483669
build nodebug fedora x86_64

00:05:16

passed #483670
build static fedora x86_64

00:17:26

passed #483671
build static nodebug fedora x86_64

00:12:42

 
  Test
passed #483678
integration testsuites fedora

00:15:30

 
  Integrate
passed #483679
documentation

00:06:12