Windows Cells not sending logs to syslog drain when posted via https.

Since we upgraded from cf-deployment 12.45.0 up to 13.7.0 and up to present 13.10.0, our windows application and cell logs are not arriving at the syslog drains which use https post.

The loggr-syslog-agent-windows logs contain the following suspicious error:
2020/09/08 15:50:21 failed to write to syslogdain.cloud.pcftest.com, retrying in 15s, err: x509: certificate signed by unknown authority. syslogdain.cloud.pcftest.com does in fact have a valid cert signed by Digicert.

I can work around this by setting drain_skip_cert_verify, but that doesn't seem optimal or desired.

Here is how I reproduce the issue:

1. Deploy an application which can accept posts like https://github.com/pusherofbrooms/syslogdrain (change manifest if you actually use this)
2. setup the service with cf cups syslogdrain -l "https://MYLOGURL"
3. setup a windows application like the one found at git@github.com:cloudfoundry-incubator/NET-sample-app.git and bind it to the syslog drain
4. restart the windows application
5. observe that no CELL or APP/PROC/WEB logs are sent to the drain application
6. observe the above err: x509 cert error in the loggr-syslog-agent-windows logs

Start with the loggr-syslog-agent-windows logs and the HTTPS syslog-drain path described in the reproduction steps. Reproduce with an HTTPS drain and a Windows application, then investigate why the valid DigiCert certificate is reported as unknown; done means CELL and APP/PROC/WEB logs arrive without disabling certificate verification.