Release SSH keys sequentially

When you hit the 5k key limit, starting 5k threads is ok for Java,
but not ok for AWS. We get immediately throttled.
It's actually faster to do it sequentially. And AWS is quick to delete.

src/main/kotlin/com/atlassian/performance/tools/aws/api/housekeeping/ConcurrentHousekeeping.kt

@@ -25,15 +25,14 @@ class ConcurrentHousekeeping(
         val amis = Ec2(aws.ec2).listExpiredAmis()
         waitUntilReleased(amis, amiTimeout)
 
-        val keys = aws.ec2.describeKeyPairs().keyPairs.map { key ->
-            RemoteSshKey(SshKeyName(key.keyName), aws.ec2)
-        }.filter { it.isExpired() }
+        aws.ec2.describeKeyPairs().keyPairs
+            .map { key -> RemoteSshKey(SshKeyName(key.keyName), aws.ec2) }
+            .filter { it.isExpired() }
+            .forEach { it.release().get() }
 
         val securityGroups = aws.ec2.describeSecurityGroups().securityGroups.map { securityGroup ->
             Ec2SecurityGroup(securityGroup, aws.ec2)
         }.filter { it.isExpired() }
-
-        waitUntilReleased(keys)
         waitUntilReleased(securityGroups)
 
         Cloudformation(aws, aws.cloudformation).consumeExpiredStacks(Consumer { stacks ->