Updating test to support Windows file descriptor count (-1)
Docs: Removing escape character

The escape character `\` doesn't work and should be removed from the documentation.

Closes #8029
Add debug logging to help diagnose intermittent upgrade test failures.

Also fixed indentation in ElasticsearchMergePolicy.
Update cat.nodes regex

Support for multi-word node names like 'Henry "Hank" McCoy'
Snapshot/Restore: fix snapshot of a single closed index

Snapshot of a closed index can leave snapshot hanging in initializing state.

Fixes #8046