[kong] Release 1.12.0 to next

[rainest]

What this PR does / why we need it:

Releases 1.12 to next. Includes several additional changes:

• Bump the default Enterprise tags to the latest 2.1 patch, 2.1.4.1.
• Increase the default worker count to 2.
• Handle deprecation warnings via a template to simplify and improve formatting.

Which issue this PR fixes

• fixes [kong] update default worker count to 2 #227
• fixes [kong] NOTES.txt warnings include extra newlines #144

Special notes for your reviewer:

Re conversations about worker count increase and memory usage from planning:

• By default, the chart does not apply memory limits to Kong deployments. However, it did include commented example limits with an unreasonably low default limit (128MB). From personal experience, this limit is too low for any deployment (even single-worker deployments), and would cause issues if applied. I've increased the commented example to 256MB, which is much more reasonable, though that's essentially a minimum lower bound for Kong to function at all rather than what I'd expect for most actual deployments. Non-demo/test environments that actually handle traffic will likely start around 1GB, and will usually have even higher limits.
• There was a brief interlude where additional workers allocated resulted in unexpected higher memory use due to removal of limits elsewhere. AFAIK we've since re-introduced those limits (chore(conf) worker_rlimit_nofile & worker_connections "auto" == max 16384 kong#5864), and increasing worker count no longer causes the consumption issues we observed in earlier 2.x releases, so I don't expect the chart change to cause issues.

We still want to explore resource usage guidelines further, but the minimums proposed here should be reasonable.

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• PR is based off the current tip of the next branch and targets next, not main
• Title of the PR and commit headers start with chart name (e.g. [kong])

[mflendrich]

LGTM but:

• this does not fix [kong] update default worker count to 2 #227 yet - after this PR, the checkbox below remains unsatisfied:

  [ ] Update the default value to 2 in Kong Ingress Controller's repository

• for future PRs, please avoid mix features and release chores in one PR

Please merge without squashing, too.

[mflendrich]

Part of #232.