stack/erp5: fix software release URL promise that was not executed

Promise from a8271791 (stack/erp5: new promise to check software
release URL of zope instances, 2020-12-04) was never executed. Adding
the section seemed to be change timing to make the upgrade test, but
this was not correct to not run the promise.

For more detail see discussion on
!1414 (comment 189341)
18 jobs for fix/erp5_soft_url_promise in 0 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  External
passed Cloudooo.UnitTest-Master

00:04:50

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster

00:34:25

running ERP5.StandaloneDeploymentScriptTest-Debian.Buster.Master

10658:35:00

passed SlapOS-Master.StandaloneDeploymentScriptTest-Debian.Buster

00:47:52

passed SlapOS.Eggs.UnitTest-Master.Python2

00:22:29

failed SlapOS.Eggs.UnitTest-Master.Python3

00:28:30

passed SlapOS.Eggs.UnitTest-TestRunner1.Python2

00:18:06

passed SlapOS.Eggs.UnitTest-TestRunner1.Python3

00:23:42

running SlapOS.SoftwareReleases.IntegrationTest-Master

10658:35:38

failed SlapOS.SoftwareReleases.IntegrationTest-TestRunner1

20:57:46

running SlapOS.Theia.ResilienceTest-Master-ERP5

10658:35:38

running Wendelin.StandaloneDeploymentScriptTest-Debian.Buster

10658:35:10

passed SlapOS.Eggs.UnitTest-TestRunner1.Python2

00:23:26

passed SlapOS.Eggs.UnitTest-TestRunner1.Python2

00:15:58

passed SlapOS.Eggs.UnitTest-TestRunner1.Python2

00:25:52

passed SlapOS.Eggs.UnitTest-TestRunner1.Python3

00:21:09

passed SlapOS.Eggs.UnitTest-TestRunner1.Python3

00:17:21

failed SlapOS.Eggs.UnitTest-TestRunner1.Python3

00:21:18