removed Action trigger from worker ModeHookError

This patches a bug in the uniter which can result in ModeHookError being
cleared by a successful Action run on the impacted unit.  Actions can no
longer be run in ModeHookError.

This will be resolved after the Context refactor on worker.
The following code (L1396 - L1408) adds the Actions before the Uniter is started, so they will be pending.  Then it starts the Uniter:

```go
		addAction{"action-log", nil},
// ...
		startUniter{},
		waitAddresses{},
		waitUnit{status: params.StatusStarted},
		waitHooks{"install", "config-changed", "start"},
		verifyCharm{},
```

This way, the next code (L1404) checks to make sure the pending Actions are indeed run after the Uniter starts.
```go
		waitHooks{
			"action-log",
			"action-log",
			"action-log",
		},
```