JSII Kernel fills disk space using CDK on Cloud9

## :bug: Bug Report

### Affected Languages

- [ ] `TypeScript` or `Javascript`
- [X] `Python`
- [ ] `Java`
- [ ] .NET (`C#`, `F#`, ...)

### General Information
* **JSII Version:**
```0.14.3```
* **Platform:**
Cloud9 Amazon Linux
```Linux ip-172-31-27-45 4.14.133-88.105.amzn1.x86_64 #1 SMP Thu Jul 11 00:44:15 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux```

### What is the problem?

Every cdk execution creates a ```jsii-kernel-XXXXXX``` directory in ```/tmp``` eventually the filesystem fills up and ```/tmp``` must be manually cleaned.

eg.
```
drwx------ 3 ec2-user ec2-user 4096 Aug 13 11:10 jsii-kernel-pAzPv3
drwx------ 3 ec2-user ec2-user 4096 Aug 13 11:12 jsii-kernel-36wtyP
drwx------ 3 ec2-user ec2-user 4096 Aug 13 11:12 jsii-kernel-VzoqYO
drwx------ 3 ec2-user ec2-user 4096 Aug 13 11:13 jsii-kernel-TxZxZE
```

### Verbose Log

https://gist.github.com/vaneek/1292391ce7a02fce283607c6d786b8ef

Start by reproducing repeated CDK executions on Cloud9 and inspect /tmp for the jsii-kernel-XXXXXX directories described in the report. Compare the kernel's temporary-directory lifecycle across executions and use the linked verbose log for context. Done means completed executions no longer leave unbounded kernel directories that require manual cleanup.

Written by the indexing model from the issue text.