fix: HA proxy memory runaway on certain rpm based distro's -> Setting maxconn in haproxy config (#15319)

[timgriffiths]

Fixes #15319

I propose the best way to fix this issue is by setting a global setting in haproxy config maxconn 4000 you can also fix it by changing the max open file limit in containerd but as this comment points out https://github.com/docker-library/haproxy/issues/194#issuecomment-1452758721 this only works as haproxy derives the max number of connections from the max open files on a system which seems like a bit of a bug or at least we should set a max as part of the config.

Setting the default sufficiently large so that this should not be a problem. this could be backported to whichever versions users need as it's a simple haproxy config tweak

Checklist:

• [x] Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
• [x] The title of the PR states what changed and the related issues number (used for the release note).
• [x] The title of the PR conforms to the Toolchain Guide
• [x] I've included "Closes [ISSUE #]" or "Fixes [ISSUE #]" in the description to automatically close the associated issue.
• [ ] I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
• [ ] Does this PR require documentation updates?
• [ ] I've updated documentation as required by this PR.
• [ ] I have signed off all my commits as required by DCO
• [ ] I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• [ ] My build is green (troubleshooting builds).
• [ ] My new feature complies with the feature status guidelines.
• [x] I have added a brief description of why this PR is necessary and/or what this PR solves.
• [ ] Optional. My organization is added to USERS.md.
• [ ] Optional. For bug fixes, I've indicated what older releases this fix should be cherry-picked into (this may or may not happen depending on risk/complexity).