v4l2-decoder-conformance: Use correct base test job

Fluster tests were previously triggered by successful kernel build in
kbuild-gcc-12-arm64-chromebook configuration. It had to be replaced by
a job depending on kbuild-gcc-12-arm64-chromeos-mediatek kernel build
events - otherwise wrong defconfig was in use.

Signed-off-by: Paweł Wieczorek <pawiecz@collabora.com>

config/scheduler-chromeos.yaml

@@ -521,35 +521,35 @@ scheduler:
  - mt8195-cherry-tomato-r2
 
  - job: fluster-chromeos-av1
- <<: *test-job-arm64-mediatek
+ <<: *test-job-chromeos-mediatek
  platforms:
  - mt8195-cherry-tomato-r2
 
  - job: fluster-chromeos-av1-chromium-10bit
- <<: *test-job-arm64-mediatek
+ <<: *test-job-chromeos-mediatek
  platforms:
  - mt8195-cherry-tomato-r2
 
  - job: fluster-chromeos-h264
- <<: *test-job-arm64-mediatek
+ <<: *test-job-chromeos-mediatek
 
  - job: fluster-chromeos-h264-frext
- <<: *test-job-arm64-mediatek
+ <<: *test-job-chromeos-mediatek
 
  - job: fluster-chromeos-h265
- <<: *test-job-arm64-mediatek
+ <<: *test-job-chromeos-mediatek
  platforms:
  - mt8195-cherry-tomato-r2
 
  - job: fluster-chromeos-vp8
- <<: *test-job-arm64-mediatek
+ <<: *test-job-chromeos-mediatek
  platforms:
  - mt8186-corsola-steelix-sku131072
  - mt8192-asurada-spherion-r0
  - mt8195-cherry-tomato-r2
 
  - job: fluster-chromeos-vp9
- <<: *test-job-arm64-mediatek
+ <<: *test-job-chromeos-mediatek
  platforms:
  - mt8186-corsola-steelix-sku131072
  - mt8192-asurada-spherion-r0