Fix: for terminals that don't send enter, submit with 'linefeed' #5969

Job	Run time
build-and-check	2m 52s
test-integration-packages/billing	1m 5s
test-integration-packages/internal	1m 11s
test-integration-sdk	1m 23s
test-integration-web	43s
test-packages/internal	52s
test-integration-packages/agent-runtime	41s
test-packages/billing	41s
test-common	47s
test-cli	53s
test-integration-common	41s
test-.agents	42s
test-integration-cli	48s
test-web	56s
test-sdk	45s
test-packages/agent-runtime	44s
	15m 44s

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