refactor: remove network as default plugin (backport #4586)

[mergify]

---

This is an automatic backport of pull request #4586 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 6f4aa5c has failed:

On branch mergify/bp/release/v28.x.y/pr-4586
Your branch is up to date with 'origin/release/v28.x.y'.

You are currently cherry-picking commit 6f4aa5c2.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   changelog.md
	modified:   ignite/cmd/plugin_default_test.go
	deleted:    integration/network/genesis.json
	deleted:    integration/network/request_test.go

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	both modified:   ignite/cmd/plugin_default.go
	both modified:   ignite/internal/tools/gen-cli-docs/main.go
	deleted by them: integration/network/network_test.go

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally