fix(coderd/rbac): reinstate deployment-wide workspace.share permission for owner role (#21620)

The removal of that permission from the role broke valid use cases (e.g.
a site owner user creating a workspace owned by a system account and
then trying to share it with another user).

The bulk of the PR is made up of the rollbacks of the previously
introduced test updates necessitated by the removal.

Related to: https://github.com/coder/internal/issues/1285

coderd/database/dbgen/dbgen.go

@@ -42,16 +42,8 @@ import (
 
 // genCtx is to give all generator functions permission if the db is a dbauthz db.
 var genCtx = dbauthz.As(context.Background(), rbac.Subject{
-	ID: "owner",
-	Roles: rbac.Roles(append(
-		must(rbac.RoleIdentifiers{rbac.RoleOwner()}.Expand()),
-		rbac.Role{
-			Identifier: rbac.RoleIdentifier{Name: "dbgen-workspace-sharer"},
-			Site: rbac.Permissions(map[string][]policy.Action{
-				rbac.ResourceWorkspace.Type: {policy.ActionShare},
-			}),
-		},
-	)),
+	ID:     "owner",
+	Roles:  rbac.Roles(must(rbac.RoleIdentifiers{rbac.RoleOwner()}.Expand())),
 	Groups: []string{},
 	Scope:  rbac.ExpandableScope(rbac.ScopeAll),
 })