v1.3.0 check thp always fail

[sultan8252]

Bug Report

When split string result, there is a \n at the end, resulting in an additional'' element in the list. Therefore, it is necessary to enter the fail process when determining whether it contains the [never] string.
bug point: https://github.com/pingcap/tiup/blob/v1.3.0/pkg/cluster/operation/check.go#L672-L677
Please answer these questions before submitting your issue. Thanks!

1. What did you do?
   tiup cluster check --cluster {cluster-name}

2. What did you expect to see?
   always report fail

3. What did you see instead?

4. What version of TiUP are you using (tiup --version)?
   v1.3.0

[dveeden]

This has been fixed by @lucklove in #1005
/close

[ti-chi-bot]

@dveeden: You can't close an active issue/PR unless you authored it or you are a collaborator.

In response to this:

This has been fixed by @lucklove in #1005
/close

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