texture-tower: Use memory management helpers more

!1496
6 jobs for !1496 with wip/cogl-framebuffer-gobject in 8 minutes and 9 seconds (queued for 1 second)
detached
Status Job ID Name Coverage
  Review
passed #943225
check-commit-log

00:00:15

 
  Build
passed #943226
build-mutter

00:03:36

passed #943228
build-without-native-backend-and-wayland

00:01:44

passed #943227
build-without-opengl-and-glx

00:01:48

 
  Test
passed #943230
can-build-gnome-shell

00:01:40

passed #943229
test-mutter

00:04:31