[BUG][Workspace]Dev server crashed after unassigning self from workspace owner

[wanglam]

Describe the bug

Dev server crashes due to unhandled promise rejection when attempting to set default data source after the current workspace owner unassigns themselves, as they are removed from the workspace permission list before this operation.

To Reproduce
Steps to reproduce the behavior:

1.Clone main branch and run yarn osd bootstrap
2.Add below configs in config/opensearch_dashboards.yml

workspace.enabled: true
savedObjects.permission.enabled: true
data_source.enabled: true
uiSettings:
  overrides:
    'home:useNewHomePage': true
opensearchDashboards.dashboardAdmin.users: ['admin']

3.Run yarn start --no-base-path
4.Login with admin user and create a test user with kibanauser role
5.Create a workspace and set test user as a workspace owner
6.Login with test user and go to workspace detail page
7.Remove test user in Collaborator tab
8.Click save button and then the dev server will crashed

Expected behavior
Dev server should not be crashed, default data source should be set

OpenSearch Version
N/A

Dashboards Version
Latest main branch

Plugins
workspace

Screenshots
N/A

Host/Environment (please complete the following information):
N/A

Additional context
#4944

[SuZhou-Joe]

closed because of #7636