Fix BatchLogRecordProcessor default schedule_delay_millis to 1000ms per OTel spec (#4998)

* Fix BatchLogRecordProcessor default schedule_delay_millis to 1000ms per OTel spec

* Update OTEL_BLRP_SCHEDULE_DELAY docstring default to 1000ms and fix CHANGELOG

* Apply suggestion from @xrmx

* Update CHANGELOG wording to 'may be' for export frequency

* Apply suggestion from @xrmx

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Co-authored-by: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>