fix(exporters): use sendBeacon with empty headers#6216

YangJonghun wants to merge 4 commits intoopen-telemetry:mainopen-telemetry/opentelemetry-js:mainfrom

YangJonghun:feat/use-beacon-with-empty-headersYangJonghun/opentelemetry-js:feat/use-beacon-with-empty-headersCopy head branch name to clipboard