ProjectCachePlugin might not get properly finlized

Details [in discussion here](https://teams.microsoft.com/l/message/19:3212bf033f4c4b5198643a04fa1048fa@thread.skype/1740085787606?tenantId=72f988bf-86f1-41af-91ab-2d7cd011db47&groupId=4ba7372f-2799-4677-89f0-7a1aaea3706c&parentMessageId=1740085787606&teamName=.NET%20Developer%20Experience&channelName=MSBuild&createdTime=1740085787606)

### Manifestation

Error in VS:

```
2>MSBUILD : error : Another instance of MSBuildCache is already running in this build. This is typically due to a misconfiguration of the plugin settings, in particular different plugin settings across projects.
```

### Cause

`ProjectCacheService.CreateAndInitializePluginAsync` creates an instance of `ProjectCachePluginBase`, but if the later initialization of the plugin (e.g. `BeginBuildAsync`) throws - the plugin is not properly 'discarded' (via call to `EndBuildAsync`).

### What needs to be done

A proper design of error contract between cache service and cache plugin needs to be defined. Specifically: what happens and is guaranteed when unrecoverable errors in between BuildManager.BeginBuild and BuildManager.EndBuild happens and the BuildManager.EndBuild is actually never called

The design needs to be sticked through by the ProjectCacheService (and the actual plugins)

FYI @dfederm