E2529: count SAM CloudWatchLogs events toward the log-group subscription limit

[kddejong]

Follow-up to #4491. Tracked in #4607. CloudWatch Logs allows 2 subscription filters per log group.

Problem

E2529 only enumerates AWS::Logs::SubscriptionFilter. SAM CloudWatchLogs events on AWS::Serverless::Function used to expand into those filters; post-#4491 they do not, so >2 SAM events on one log group are not flagged. test_events_log_group_name::test_file_negative was set to expect 0.

Fix

In __get_log_group_name_list, also read AWS::Serverless::Function Events of Type: CloudWatchLogs and merge their LogGroupName into the same per-group buckets as explicit filters.

Acceptance

• Flags >2 SAM events on one group
• Flags mixed explicit+SAM >2 on one group
• Match path at Resources/<Fn>/Properties/Events/<Id>/...
• isinstance guards for non-dict/intrinsic Events
• Flip bad/some_logs_stream_lambda.yaml back to 1 error