ACCUMULO-1858 revert commits that added ZooKeeperInstance.close()

Revert "ACCUMULO-2027 Synchronized access to ZooKeeperInstance methods that mutated state"

This reverts commit 975e8c05e8d11f3848e6c800f4d2772026f6c3a3.

Revert "ACCUMULO-1984 Rework interruption for instance implementations."

This reverts commit 0d0bc4643a8680593e2cf5f828b7566c30fcb345.

Conflicts:
	src/core/src/main/java/org/apache/accumulo/core/client/Instance.java
	src/core/src/main/java/org/apache/accumulo/core/zookeeper/ZooCache.java
	src/core/src/main/java/org/apache/accumulo/core/zookeeper/ZooReader.java

Revert "ACCUMULO-1889 mark ZKI as closed once close() is called."

This reverts commit ada4180379d46297c1531cf8065de5030d12953d.

Revert "ACCUMULO-1858 Backport ZooKeeper clean up to 1.4 and 1.5."

This reverts commit 79d686faa1e477b9cbd80c6f833ece402050b490.

Conflicts:
	src/core/src/main/java/org/apache/accumulo/core/client/Instance.java
	src/core/src/main/java/org/apache/accumulo/core/zookeeper/ZooCache.java