fix(saml): Push AuthenticationSucceededOnApplication milestone for SAML sessions (#10263)

# Which Problems Are Solved

The SAML session (v2 login) currently does not push a
`AuthenticationSucceededOnApplication` milestone upon successful SAML
login for the first time. The changes in this PR address this issue.

# How the Problems Are Solved

Add a new function to set the appropriate milestone, and call this
function after a successful SAML request.

# Additional Changes

N/A

# Additional Context

- Closes #9592

---------

Co-authored-by: Stefan Benz <46600784+stebenz@users.noreply.github.com>

internal/command/saml_session.go

@@ -80,7 +80,15 @@ func (c *Commands) CreateSAMLSessionFromSAMLRequest(ctx context.Context, samlReq
 		return err
 	}
 	cmd.SetSAMLRequestSuccessful(ctx, samlReqModel.aggregate)
+	postCommit, err := cmd.SetMilestones(ctx)
+	if err != nil {
+		return err
+	}
 	_, err = cmd.PushEvents(ctx)
+	if err != nil {
+		return err
+	}
+	postCommit(ctx)
 	return err
 }