small UI regressions in convert Vmware to KVM VMs

[DaanHoogland]

problem

1. When trying to convert Vmware to KVM VMs a new search is done for every change in the entry fields and the faulty results should be ignored, but are reported.
2. it is not possibel to unselect the host in the ESXi host to search for all VMs on all hosts
3. the label says "vCenter host" instead of "ESXi host"

versions

ACS 4.19.2-rc3

The steps to reproduce the bug

1.go to tools -> Import-Export Instances
2.select "Migrate existing instances to KVM"
3.select "External" below the label "Select the source VMware vCenter Datacenter"
4.start filling the fields below
...

What to do about it?

ui fixes

[DaanHoogland]

during testing of this an NPE was encountered:

java.lang.NullPointerException
        at com.cloud.hypervisor.vmware.mo.BaseMO.createReturnObjectPair(BaseMO.java:68)
        at com.cloud.hypervisor.vmware.mo.HostMO.getVmProperties(HostMO.java:760)
        at com.cloud.hypervisor.vmware.mo.HostMO.getVmProperties(HostMO.java:1399)
        at com.cloud.hypervisor.vmware.mo.HostMO.getVms(HostMO.java:1379)
        at com.cloud.hypervisor.vmware.manager.VmwareManagerImpl.listVMsInDatacenter(VmwareManagerImpl.java:1605)
        at jdk.internal.reflect.GeneratedMethodAccessor473.invoke(Unknown Source)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.jav
a:198)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
        at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215)
        at com.sun.proxy.$Proxy447.listVMsInDatacenter(Unknown Source)
        at org.apache.cloudstack.api.command.admin.zone.ListVmwareDcVmsCmd.execute(ListVmwareDcVmsCmd.java:121)
        at com.cloud.api.ApiDispatcher.dispatch(ApiDispatcher.java:172)
        at com.cloud.api.ApiServer.queueCommand(ApiServer.java:833)
        at com.cloud.api.ApiServer.handleRequest(ApiServer.java:654)
        at com.cloud.api.ApiServlet.processRequestInContext(ApiServlet.java:349)
        at com.cloud.api.ApiServlet$1.run(ApiServlet.java:152)
        at org.apache.cloudstack.managed.context.impl.DefaultManagedContext$1.call(DefaultManagedContext.java:55)
        at org.apache.cloudstack.managed.context.impl.DefaultManagedContext.callWithContext(DefaultManagedContext.java
:102)
        at org.apache.cloudstack.managed.context.impl.DefaultManagedContext.runWithContext(DefaultManagedContext.java:
52)
        at com.cloud.api.ApiServlet.processRequest(ApiServlet.java:149)
        at com.cloud.api.ApiServlet.doGet(ApiServlet.java:103)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:645)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:750)
        at org.eclipse.jetty.servlet.ServletHolder$NotAsync.service(ServletHolder.java:1450)

this is addressed in 9b2a83d

[DaanHoogland]

fixed in #10413