Be extra lenient for non-Sun JDK perf tests

The slack factor for non-Sun JDK performance test in PackagingDataCalculatorTest
was not lenient enough for the small virtual nodes on Cloudbees Jenkins.
Some people were also reporting test failures here by a few percentage points
(on their slow development machines).

Bump slack factor from 10 to 15
Fix RecoveryCoordinatorTest

Use new instance of RecoveryCoordinator in each test. Otherwise, the timestamp
of the next call to isTooSoon() could happen well after the backoff threshold
on slow machines (such as small nodes on Cloudbees Jenkins), causing false
test failures.

This also renames and refines the individual tests.