improve: add license headers to source files #5606

Job	Run time
check_format_and_unit_tests	1m 23s
build / Special integration tests (17)	2m 19s
build / Special integration tests (21)	2m 37s
build / Special integration tests (24)	2m 24s
build / httpclient-tests (jetty) / Integration tests (24, 1.32.0, jetty)	22m 41s
build / httpclient-tests (jdk) / Integration tests (24, 1.32.0, jdk)	23m 11s
build / httpclient-tests (vertx) / Integration tests (24, 1.32.0, vertx)	22m 32s
build / integration_tests (24, 1.30.12) / Integration tests (24, 1.30.12, vertx)	22m 18s
build / integration_tests (21, 1.30.12) / Integration tests (21, 1.30.12, vertx)	21m 55s
build / integration_tests (17, 1.32.4) / Integration tests (17, 1.32.4, vertx)	23m 36s
build / integration_tests (21, 1.32.4) / Integration tests (21, 1.32.4, vertx)	23m 17s
build / integration_tests (17, 1.30.12) / Integration tests (17, 1.30.12, vertx)	22m 45s
build / integration_tests (24, 1.31.8) / Integration tests (24, 1.31.8, vertx)	22m 3s
build / integration_tests (24, 1.33.1) / Integration tests (24, 1.33.1, vertx)	23m 55s
build / integration_tests (21, 1.31.8) / Integration tests (21, 1.31.8, vertx)	23m 13s
build / integration_tests (17, 1.31.8) / Integration tests (17, 1.31.8, vertx)	22m 56s
build / integration_tests (17, 1.33.1) / Integration tests (17, 1.33.1, vertx)	23m 23s
build / integration_tests (21, 1.33.1) / Integration tests (21, 1.33.1, vertx)	23m 25s
build / integration_tests (24, 1.32.4) / Integration tests (24, 1.32.4, vertx)	23m 35s
	5h 53m 28s

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