refactor(tools): update all references to tools.rand

[chronolaw]

Summary

KAG-3143

Checklist

• The Pull Request has tests
• A changelog file has been created under changelog/unreleased/kong or skip-changelog label added on PR if changelog is unnecessary. README.md
• There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Issue reference

Fix #[issue number]

[hanshuebner]

@bungle expressed concern about this change: Even though we don't like it, we need to consider that our customers use plugins that are forks of plugins that we wrote and that use internal functions, like those from kong.utils. Reorganizational refactorings like provide only small improvements in the grand scheme of things, but they bear substantial risks when customers rely on interfaces that are removed this way.

I think we should rather audit all plugins that we can get our hands on to determine what internal functions they call, add those functions to the PDK and update the plugins to use them from there. Once we've done that, we can do the internal thing.

We could also split up kong.utils, but keep the old interfaces for backwards compatibility.

@kikito

Backward compatibility concerns

[chronolaw]

Should we revert this commit? 02aab49

[chronolaw]

After a short discussion, we decided that to keep the utils.* apis for compatibility, @hanshuebner , do you think it is OK now?

Makes sense.

[Water-Melon]

LGTM