fix logic filtering smart stacks

prior implementation was incorrect and after testing learned SMARTSTACK
represents an unique id for smart stack images. Changed logic to mimic
frontend implementation of removing intermediates. Creating a dict of
max stknum smart stacks and then using list comprehension to build a new
list of only the max stknums and non smart stack images. Tested and working
properly.

api/db.py

@@ -288,17 +288,34 @@ def filtered_images_query(db_address: str, query_filters: list):
             .all()
         session.expunge_all()
     image_pkgs = [image.get_image_pkg() for image in images]
-    image_pkgs = list(filter(filter_img_pkgs_final_sstack, image_pkgs))
+    image_pkgs = filter_img_pkgs_final_sstack(image_pkgs)
     return image_pkgs
 
 # Filter smart stacks to reduce the size of ui payload
-def filter_img_pkgs_final_sstack(img_pkg):
-    try:
-        if img_pkg["SMARTSTK"] == 'no' or img_pkg["SMARTSTK"] == img_pkg["SSTKNUM"]:
-            return True
-        return False
-    except KeyError :
-        return True
+def filter_img_pkgs_final_sstack(image_pkgs):
+    # dict containing max stknum for each unique smartstack
+    max_sstk_nums = {}
+
+    for img_pkg in image_pkgs:
+        smart_stk = img_pkg.get('SMARTSTK')
+        sstk_num = img_pkg.get('SSTKNUM')
+
+        if smart_stk is None or smart_stk == 'no':
+            continue
+
+        if smart_stk not in max_sstk_nums or sstk_num > max_sstk_nums[smart_stk]:
+            max_sstk_nums[smart_stk] = sstk_num
+
+    # keep non intermediate img_pkgs, non smart stack img_pkgs, and img_pkgs missing smart stack keys
+    filtered_arr = [
+        img_pkg for img_pkg in image_pkgs
+        if img_pkg.get('SMARTSTK') is None
+        or img_pkg.get('SSTKNUM') is None
+        or img_pkg.get('SMARTSTK') == 'no'
+        or img_pkg['SSTKNUM'] >= max_sstk_nums.get(img_pkg.get('SMARTSTK'), 0)
+    ]
+
+    return filtered_arr
 
 def get_image_by_filename(db_address, base_filename):
     """Gets the image package for the image specified by the filename.