TestRtpStreamSend: ASAN, fix buffer overflow #4710

Job	Run time
ci (ubuntu-20.04, 18, Release)	6m 15s
ci (ubuntu-20.04, 18, Debug)	5m 33s
ci (ubuntu-22.04, 20, Release)	6m 2s
ci (ubuntu-22.04, 20, Debug)	5m 17s
ci (ubuntu-24.04, 20, -Db_sanitize=address, Release)	8m 39s
ci (ubuntu-24.04, 20, -Db_sanitize=address, Debug)	6m 6s
ci (ubuntu-24.04, 20, -Db_sanitize=undefined, Release)	9m 32s
ci (ubuntu-24.04, 20, -Db_sanitize=undefined, Debug)	6m 22s
ci (ubuntu-24.04, 20, -Db_sanitize=thread, Release)	7m 2s
ci (ubuntu-24.04, 20, -Db_sanitize=thread, Debug)	5m 56s
ci (macos-12, 18, Release)	9m 45s
ci (macos-12, 18, Debug)	7m 5s
ci (macos-14, 20, Release)	4m 1s
ci (macos-14, 20, Debug)	4m 9s
ci (windows-2022, 20, Release)	9m 15s
ci (windows-2022, 20, Debug)	7m 55s
	1h 48m 54s

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