This PR reverts changes related to tag-based cluster membership. As discussed in SPARK-3332, we didn't figure out a safe strategy to use tags to determine cluster membership, because tagging is not atomic. The following changes are reverted:

SPARK-2333: 94053a7b
SPARK-3213: 7faf755a
SPARK-3608: 78d4220f.

I tested launch, login, and destroy. It is easy to check the diff by comparing it to Josh's patch for branch-1.1:

https://github.com/apache/spark/pull/2225/files

JoshRosen I sent the PR to master. It might be easier for us to keep master and branch-1.2 the same at this time. We can always re-apply the patch once we figure out a stable solution.

Author: Xiangrui Meng <meng@databricks.com>

Closes #3453 from mengxr/SPARK-4509 and squashes the following commits:

f0b708b [Xiangrui Meng] revert 94053a7b
4298ea5 [Xiangrui Meng] revert 7faf755a
35963a1 [Xiangrui Meng] Revert "SPARK-3608 Break if the instance tag naming succeeds"