test_compose_tar: Fix docker test

The docker phase always failed because `-ti` was passed even though the
the output was not a terminal.

Also remove the check for /usr/bin/docker in the setup phase. It didn't
test that the daemon was running. More importantly, it didn't abort the
test anwyay (and there doesn't seem to be a good way to do this in
beakerlib).

tests/cli/test_compose_tar.sh

@@ -13,10 +13,6 @@ CLI="${CLI:-./src/bin/composer-cli}"
 
 
 rlJournalStart
-    rlPhaseStartSetup
-        rlAssertExists /usr/bin/docker
-    rlPhaseEnd
-
     rlPhaseStartTest "compose start"
         rlAssertEquals "SELinux operates in enforcing mode" "$(getenforce)" "Enforcing"
         UUID=`$CLI compose start example-http-server tar`
@@ -43,7 +39,7 @@ rlJournalStart
         rlRun -t -c "docker import $IMAGE composer/$UUID:latest"
 
         # verify we can run a container with this image
-        rlRun -t -c "docker run -it --rm --entrypoint /usr/bin/cat composer/$UUID /etc/redhat-release"
+        rlRun -t -c "docker run --rm --entrypoint /usr/bin/cat composer/$UUID /etc/redhat-release"
     rlPhaseEnd
 
     rlPhaseStartTest "Verify tar image with systemd-nspawn"