Remove logic for parsing dismiss rule

We now still parse dismiss_rule from activity metadata, but intead of
treating it as "first show on Day x, then on day y if user dismiss
suggestion", we simply start showing suggestion on day x. If user
dismisses the suggestion, it's gone forever.

Change-Id: Ia4d14167a407983df22e582f8dbab0c2cc153e1e
Fix: 64297191
Test: robotests