Remove unused tags certified-8

[faandg]

Certified edition for java 8 should not exist according to the information on this page (only for Open edition):

However, there are images listed for it in icr.io/appcafe for it:
(This extract is from ibmcloud cr images --restrict appcafe)

icr.io/appcafe/ibm-semeru-runtimes                    certified-8-jdk-focal                                        9d23fb26fef6   appcafe     -               106 B    -
icr.io/appcafe/ibm-semeru-runtimes                    certified-8-jdk-jammy                                        9d23fb26fef6   appcafe     -               106 B    -
icr.io/appcafe/ibm-semeru-runtimes                    certified-8-jdk-ubi                                          9d23fb26fef6   appcafe     -               106 B    -
icr.io/appcafe/ibm-semeru-runtimes                    certified-8-jdk-ubi-minimal                                  9d23fb26fef6   appcafe     -               106 B    -
icr.io/appcafe/ibm-semeru-runtimes                    certified-8-jdk-ubi9                                         9d23fb26fef6   appcafe     -               106 B    -
icr.io/appcafe/ibm-semeru-runtimes                    certified-8-jdk-ubi9-minimal                                 9d23fb26fef6   appcafe     -               106 B    -
icr.io/appcafe/ibm-semeru-runtimes                    certified-8-jre-focal                                        9d23fb26fef6   appcafe     -               106 B    -
icr.io/appcafe/ibm-semeru-runtimes                    certified-8-jre-jammy                                        9d23fb26fef6   appcafe     -               106 B    -
icr.io/appcafe/ibm-semeru-runtimes                    certified-8-jre-ubi                                          9d23fb26fef6   appcafe     -               106 B    -
icr.io/appcafe/ibm-semeru-runtimes                    certified-8-jre-ubi-minimal                                  9d23fb26fef6   appcafe     -               106 B    -
icr.io/appcafe/ibm-semeru-runtimes                    certified-8-jre-ubi9                                         9d23fb26fef6   appcafe     -               106 B    -
icr.io/appcafe/ibm-semeru-runtimes                    certified-8-jre-ubi9-minimal                                 9d23fb26fef6   appcafe     -               106 B    -

They are empty references.
Hence, trying to pull or inspect the images fails:

➜  ~ podman pull icr.io/appcafe/ibm-semeru-runtimes:certified-8-jre-ubi9-minimal
Trying to pull icr.io/appcafe/ibm-semeru-runtimes:certified-8-jre-ubi9-minimal...
Error: choosing an image from manifest list docker://icr.io/appcafe/ibm-semeru-runtimes:certified-8-jre-ubi9-minimal: no image found in manifest list for architecture "amd64", variant "", OS "linux"

➜  ~ skopeo inspect docker://icr.io/appcafe/ibm-semeru-runtimes:certified-8-jre-ubi9-minimal
FATA[0001] Error parsing manifest for image: choosing image instance: no image found in manifest list for architecture amd64, variant "", OS linux

➜  ~ skopeo inspect --raw docker://icr.io/appcafe/ibm-semeru-runtimes:certified-8-jre-ubi9-minimal
{"schemaVersion":2,"mediaType":"application/vnd.docker.distribution.manifest.list.v2+json","manifests":[]}

I suggest removing them to prevent confusion.