[infra] When killing a process on Windows don't double-check the name.

tasklist truncates process name:
```
PS C:\src\d\sdk> tasklist /fi "imagename eq dartaotruntime_product.exe" /nh

dartaotruntime_product.ex    27060 Console                    1    123,188 K
```

Follow-up to 9acd26ee8b.

Change-Id: I2cf08548ae478b2f2d750862fecc1424852e47b9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/404363
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Commit-Queue: Alexander Aprelev <aam@google.com>

tools/task_kill.py

@@ -141,7 +141,7 @@ def GetPidsWindows(process_name):
 
     for line in lines:
         split = line.split()
-        if len(split) > 2 and split[0] == process_name:
+        if len(split) > 2:
             results.append(split[1])
     return results