test: move make-tags.sh into test/

Move the make-tags.sh helper into the `test/` sub-directory. It is
mainly needed for testing together with the other test scripts.

HACKING.md

@@ -95,7 +95,7 @@ A helper script will create a minimum set that is necessary to build
 an image call `Fedora-Cloud` for `f32-candidate`:
 
 ```sh
-./make-tags.sh
+test/make-tags.sh
 ```
 
 ### Client plugin

test/integration.sh

@@ -62,7 +62,7 @@ greenprint "Starting koji builder"
 sudo ./run-builder.sh start
 
 greenprint "Creating Koji tag infrastructure"
-./make-tags.sh
+test/make-tags.sh
 
 greenprint "Running integration tests"
 python3 -m unittest discover -v test/integration/