removes redundant vector allocations before calling sendmmsg::batch_send #8116

Job	Run time
ios (macos-13, aarch64-apple-ios)	3m 5s
android (ubuntu-20.04, x86_64-linux-android)	2m 13s
ios (macos-13, x86_64-apple-ios)	2m 48s
android (ubuntu-20.04, aarch64-linux-android)	2m 31s
ios (macos-13, aarch64-apple-darwin)	3m 29s
android (ubuntu-20.04, i686-linux-android)	2m 24s
ios (macos-13, x86_64-apple-darwin)	2m 39s
android (ubuntu-20.04, armv7-linux-androideabi)	5m 8s
error_reporting	0s
	24m 17s

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