test: use ADD for ejabberd test #681

Job	Run time
prepare (mainline)	27s
prepare (buildkit)	8s
prepare (desktop)	33s
e2e (mainline, pip-youtube-dl, linux/arm/v7)	1m 21s
e2e (mainline, webpack, linux/arm/v7)	1m 54s
validate (./hack/lint)	30s
test (mainline)	3m 38s
e2e (desktop, pip-youtube-dl, linux/arm/v7)	1m 25s
validate (./hack/validate-vendor)	22s
test (buildkit)	38s
e2e (desktop, webpack, linux/arm/v7)	1m 55s
validate (./hack/install-and-test)	34s
test (desktop)	10s
e2e (mainline, ejabberd, linux/arm64)	57s
e2e (desktop, tini, linux/arm64, --rm)	39s
e2e (desktop, postgis, linux/arm64, -d --name postgis, postgis, UTC [1] LOG: database system is ...	46s
build	0s
	15m 57s

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