[chore][cmd/opampsupervisor] Add manual time.Sleep call (#42551)

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#### Description

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Updates #42458 to adapt to stretchr/testify#1427

Author: mx-psi

cmd/opampsupervisor/e2e_test.go

@@ -2116,6 +2116,8 @@ func TestSupervisorRemoteConfigApplyStatus(t *testing.T) {
 				},
 			})
 
+			// TODO: Remove time.Sleep below, see https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/42550
+			time.Sleep(100 * time.Millisecond)
 			// Check that the status is set to APPLYING
 			require.Eventually(t, func() bool {
 				status := remoteConfigStatus.Load().(*protobufs.RemoteConfigStatus)