vulkan: fix some leaks

Fix vk_instance leak when state change fails like in
generic/states unit test.
8 jobs for fix-leaks in 49 minutes and 43 seconds (queued for 3 minutes and 30 seconds)
Status Job ID Name Coverage
  Preparation
passed #159948
gst indent

00:01:19

passed #159947
manifest

00:00:48

 
  Build
passed #159949
build fedora x86_64

00:05:46

 
  Test
passed #159950
check fedora

00:03:59

 
  Full Builds
passed #159951
build android arm64 api28

00:04:28

passed #159953
build cerbero cross win32

00:11:24

passed #159954
build cerbero cross win64

00:09:43

passed #159952
build cerbero fedora x86_64

00:12:14