clean up older compatibility test images (#5687)

Signed-off-by: Ben Ye <benye@amazon.com>

Author: yeya24

.github/workflows/test-build-deploy.yml

@@ -146,12 +146,6 @@ jobs:
           docker pull consul:1.8.4
           docker pull gcr.io/etcd-development/etcd:v3.4.7
           if [ "$TEST_TAGS" = "integration_backward_compatibility" ]; then
-            docker pull quay.io/cortexproject/cortex:v1.6.0
-            docker pull quay.io/cortexproject/cortex:v1.7.0
-            docker pull quay.io/cortexproject/cortex:v1.8.0
-            docker pull quay.io/cortexproject/cortex:v1.9.0
-            docker pull quay.io/cortexproject/cortex:v1.10.0
-            docker pull quay.io/cortexproject/cortex:v1.11.1
             docker pull quay.io/cortexproject/cortex:v1.13.1
             docker pull quay.io/cortexproject/cortex:v1.13.2
             docker pull quay.io/cortexproject/cortex:v1.14.0

integration/backward_compatibility_test.go

@@ -21,12 +21,6 @@ var (
 	// If you change the image tag, remember to update it in the preloading done
 	// by GitHub Actions too (see .github/workflows/test-build-deploy.yml).
 	previousVersionImages = map[string]func(map[string]string) map[string]string{
-		"quay.io/cortexproject/cortex:v1.6.0":  preCortex110Flags,
-		"quay.io/cortexproject/cortex:v1.7.0":  preCortex110Flags,
-		"quay.io/cortexproject/cortex:v1.8.0":  preCortex110Flags,
-		"quay.io/cortexproject/cortex:v1.9.0":  preCortex110Flags,
-		"quay.io/cortexproject/cortex:v1.10.0": nil,
-		"quay.io/cortexproject/cortex:v1.11.1": nil,
 		"quay.io/cortexproject/cortex:v1.13.1": nil,
 		"quay.io/cortexproject/cortex:v1.13.2": nil,
 		"quay.io/cortexproject/cortex:v1.14.0": nil,