fix: prometheus rule overrides swaps whole list

[csatib02]

• The Prometheus-rule override functionality was faulty, because the original implementation had a sequential override problem where each subsequent override would replace the previous one completely, rather than applying multiple overrides cumulatively.
• The conditional check inside the Override() method doesn't actually prevent the method from returning a rule - it just conditionally modifies the rule.
• These issues combined would lead to creating duplicate or unnecessary modified versions of all rules, while swapping the whole list every iteration, rather than selectively overriding only the rules that match specific criteria.

Fixes: #1842