Fix auto-declaration with local counters

[xsedla1o]

Fix event auto-declaration when local counters are enabled through sync_interval or sync_limit.

EventGroup.declare_event_id() previously iterated over the interval names in self.counters instead of the interval counter dictionaries. Logging an unknown event with both auto_declare_events and local counters enabled therefore raised a TypeError.

The declaration now:

• initializes the event in every interval counter dictionary;
• performs counter initialization under counter_lock, preventing races with logging and synchronization;
• publishes the event ID only after its local counters have been initialized.

This has gone unnoticed as configurations used a sync-interval key with - instead of _, which disabled local counters silently.

A regression test covers declaring, logging, and synchronizing a dynamic event across multiple intervals.

python -m unittest discover -s tests -v

Ran 1 test in 0.001s
OK