tests: fix prompting test

The prompting test was relying on formerly broken semantics of `owner`
prefix rules. This is actually fixed by 4.1.x and so the test was
failing, as the files in question were not owned by the test user.

Fix this by chowning the directory and the file.

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>

Author: zyga

tests/main/apparmor-prompting-smoke/task.yaml

@@ -112,9 +112,11 @@ execute: |
     case "$INTERFACE" in
         "home")
             mkdir -p "$TARGET_DIR"
+            chown test:test "$TARGET_DIR"
             # create and add text to the target file
             TARGET_FILE="$TARGET_DIR/foo"
             echo "hello-foo" > "$TARGET_FILE"
+            chown test:test "$TARGET_FILE"
             PERMISSION="read"
             # the constraint used in the prompt response
             CONSTRAINT="{\"path-pattern\": \"$TARGET_FILE\", \"permissions\": [\"$PERMISSION\"]}"