Disable HTTP/2 protocol in `devfile/registry-support` to mitigate `CVE-2023-44487` (Rapid Reset)

[rm3l]

/kind task
/area registry

This is a follow-up issue to #1315.

As commented out in #1315 (comment)_, it is strongly recommended, as one of the possible mitigation measures, to disable HTTP/2 endpoints if not needed: https://access.redhat.com/security/cve/CVE-2023-44487

And from this analysis, there seems to be currently only one repo where we need to do so:

• devfile/registry-support: in the index/server folder, where an HTTP Server is started

The steps for disabling the HTTP/2 protocol in net/http are documented in https://pkg.go.dev/net/http#hdr-HTTP_2

Acceptance Criteria

• Disable HTTP/2 protocol in servers started in the devfile/registry-support repo
• Make sure it doesn't break the way existing clients interact with registries

[thepetk]

I've created a PR which follows the instructions mentioned in the pkg.go.dev

[thepetk]

Updating the story points needed for the issue from 3 to 5, as the review process required more time.