execution listener of timer event does not work in some event

**Describe the bug**
Timer Boundary Event: the execution listener only execute call-back in end event.
Timer Intermediate Event: the execution listener only execute call-back in start event.
For example: in xml below, these execution listener can't execute call-back.
What's more, when instance ended, the system will print error log:
```
org.flowable.common.engine.api.FlowableException: No process instance found with id 7d1a8ba1-031d-11ed-912c-d21770d64551
at org.flowable.rest.service.api.runtime.process.ProcessInstanceNodeResource.getModelJSON(ProcessInstanceNodeResource.java:88) ~[flowable-rest-6.7.0.jar!/:6.7.0]
at sun.reflect.GeneratedMethodAccessor266.invoke(Unknown Source) ~[na:na]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_242]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_242]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:197) ~[spring-web-5.3.9.jar!/:5.3.9]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141) ~[spring-web-5.3.9.jar!/:5.3.9]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106) ~[spring-webmvc-5.3.9.jar!/:5.3.9]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.9.jar!/:5.3.9]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.9.jar!/:5.3.9]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.9.jar!/:5.3.9]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1064) ~[spring-webmvc-5.3.9.jar!/:5.3.9]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.9.jar!/:5.3.9]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) [spring-webmvc-5.3.9.jar!/:5.3.9]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) [spring-webmvc-5.3.9.jar!/:5.3.9]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) [tomcat-embed-core-9.0.52.jar!/:na]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) [spring-webmvc-5.3.9.jar!/:5.3.9]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) [tomcat-embed-core-9.0.52.jar!/:na]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) [tomcat-embed-core-9.0.52.jar!/:na]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.52.jar!/:na]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) [tomcat-embed-websocket-9.0.52.jar!/:na]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.52.jar!/:na]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.52.jar!/:na]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:327) [spring-security-web-5.5.2.jar!/:5.5.2]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:115) [spring-security-web-5.5.2.jar!/:5.5.2]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:81) [spring-security-web-5.5.2.jar!/:5.5.2]
...
```

**Expected behavior**
The Execution listener should execute call-back in all start, take, end events.
Don't print error log.

**Code**
```




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```
```





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```
**Additional context**
I use flowable 6.7.0, database is mysql and only use flowable-app-rest module.