tests: Allow skipping image build in compose sanity test

when $SKIP_IMAGE_BUILD is set the test skips 2 phases:
- start the compose again (after it has been cancelled) and
- waiting for it to finish & downloading the resulting image

This will allow to enable this test script in downstream gating
jobs.

Cherry-picked from cc29b99659,
https://github.com/weldr/lorax/pull/1053/

Related: rhbz#1825190

tests/cli/test_compose_sanity.sh

@@ -59,10 +59,10 @@ rlJournalStart
             until $CLI compose info $UUID | grep 'RUNNING'; do
                 sleep 20
                 rlLogInfo "Waiting for compose to start running..."
-		if $CLI compose info $UUID | grep 'FAILED'; then
+                if $CLI compose info $UUID | grep 'FAILED'; then
-		      rlFail "Compose FAILED!"
+                      rlFail "Compose FAILED!"
-		      break
+                      break
-		fi	      
+                fi
             done;
         else
             rlFail "Compose UUID is empty!"
@@ -76,6 +76,7 @@ rlJournalStart
         fi
     rlPhaseEnd
 
+if [ -z "$SKIP_IMAGE_BUILD" ]; then
     rlPhaseStartTest "compose start again"
         UUID=`$CLI compose start test-http-server qcow2`
         rlAssertEquals "exit code should be zero" $? 0
@@ -83,14 +84,6 @@ rlJournalStart
         UUID=`echo $UUID | cut -f 2 -d' '`
     rlPhaseEnd
 
-    rlPhaseStartTest "compose info"
-        if [ -n "$UUID" ]; then
-            rlRun -t -c "$CLI compose info $UUID | egrep 'RUNNING|WAITING'"
-        else
-            rlFail "Compose UUID is empty!"
-        fi
-    rlPhaseEnd
-
     rlPhaseStartTest "compose image"
         wait_for_compose $UUID
         if [ -n "$UUID" ]; then
@@ -107,9 +100,14 @@ rlJournalStart
             rlAssertNotDiffer "/var/lib/lorax/composer/results/$UUID/disk.qcow2" "$UUID-disk.qcow2"
         fi
     rlPhaseEnd
+else
+    rlLogInfo "Skipping image build phases"
+fi
 
     rlPhaseStartCleanup
-        rlRun -t -c "$CLI compose delete $UUID"
+        if [ "$($CLI compose list | grep -c $UUID)" == "1" ]; then
+            rlRun -t -c "$CLI compose delete $UUID"
+        fi
     rlPhaseEnd
 
 rlJournalEnd