update proxy tests

[timmy-wright]

What type of PR is this?

/kind bug

What this PR does / why we need it:

• curl can use both the upper case and lower case versions of HTTP_PROXY, HTTPS_PROXY, and NO_PROXY
• it prefers the lower case one if both are there.
• We are setting both in /etc/environment (in cse_config.sh), but not both in this file.
• So it makes sense to set both here.

Which issue(s) this PR fixes:

Requirements:

• [ ] uses conventional commit messages
• [ ] includes documentation
• [ ] adds unit tests
• [ ] tested upgrade from previous version

Special notes for your reviewer:

Release note:

Set both upper and lower case shell variables HTTP_PROXY, HTTPS_PROXY, and NO_PROXY during bootstrapping.