chore: add portal-designer to devstack #597

Job	Run time
run_ci (ubuntu-20.04, 3.11, discovery+lms+forum)	21m 49s
run_ci (ubuntu-20.04, 3.11, registrar+lms)	17m 15s
run_ci (ubuntu-20.04, 3.11, ecommerce+lms)	22m 7s
run_ci (ubuntu-20.04, 3.11, edx_notes_api+lms)	16m 49s
run_ci (ubuntu-20.04, 3.11, credentials+lms)	18m 6s
run_ci (ubuntu-20.04, 3.11, xqueue)	3m 4s
run_ci (ubuntu-20.04, 3.11, analyticsapi+insights+lms)	23m 29s
run_ci (ubuntu-20.04, 3.11, designer+lms)	18m 10s
run_ci (ubuntu-20.04, 3.11, enterprise-catalog+enterprise-access+lms)	22m 45s
run_ci (ubuntu-20.04, 3.11, license-manager+lms)	18m 5s
	3h 1m 39s

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