Unify Scanner and Collector determine-image-tag tasks

and add notes to later unify with the StackRox one.

Scanner can be unified with Collector thanks to
stackrox/scanner#1742

It could be that the ultimate unification will come in
https://issues.redhat.com/browse/ROX-26026 but I created a new task
anyway.

Author: msugakov

tasks/determine-image-tag-scanner-task.yaml

@@ -3,6 +3,7 @@ kind: Task
 metadata:
   name: determine-image-tag-stackrox
 spec:
+  # TODO(ROX-27384): this is a special task for the StackRox repo, unify with Scanner and Collector ones.
   description: Determines the tag for the output image using the StackRox convention from 'make tag' output.
   params:
   - name: TAG_SUFFIX

tasks/determine-image-tag-stackrox-task.yaml

@@ -1,8 +1,9 @@
 apiVersion: tekton.dev/v1
 kind: Task
 metadata:
-  name: determine-image-tag-collector
+  name: determine-image-tag
 spec:
+  # TODO(ROX-27384): this is a task for Scanner and Collector repos, unify with the StackRox one.
   description: Determines the tag for the output image using the StackRox convention from 'make tag' output.
   params:
   - name: TAG_SUFFIX