The Root Certificate doesnot regenerate once deleted from the bin folder

**Vikash kumar gupta** ([Bug 62845](https://bz.apache.org/bugzilla//show_bug.cgi?id=62845&redirect=false)):
Jmeter will generate the root certificate in the bin folder only once. If the certificate is deleted, Jmeter will not regenerate the certificate again but the message box appears that root certificate is generated.

How to reproduce:
1. Open Jmeter 5.0. Add test script recorder under Test Plan. CLick on start button. Jmeter shows msg that root cert is generated in bin folder and the certificate is indeed generated.
2. Now delete the certificate.
3. Click again the start button in the test script recorder.
4. Jmeter will show dialog saying root cert is generated under bin folder
5. Now navigate to bin folder and you will not find the certificate.

Expected outcome: If the root cert is deleted, Jmeter should regenerate the certificate.

OS: All