Sort out repository labels

[tisonkun]

What type of enhancement is this?

Other

What does the enhancement do?

We gradually define a lot of labels in this repository. To give developers an intuitive impression and avoid some common mistakes, I suppose we sort out the labels with a few best practices.

1. Retain automation labels. For example, dependabot uses Dependency label, and we just leave it as is. The contribute page depends on good first issue label, and we should leave it as is.
2. Avoid whitespace. For other labels, avoid whitespace, so that we can parse it more reliably.
3. Drop Difficulty labels since it's often hard to say. We have good first issue to identify relative easy issue already; others are by default need some investigation.
4. Drop Priority labels since we don't use them.

So, following the pattern from how CockroachDB defines labels, I suppose we have the following labels:

• good first issue
• help wanted
• breaking-change
• release-blocker
• tracking-issue

Follow-ups: see #3855.

Origins:

• O-fuzz (found by fuzz)
• O-end-to-end (found by end-to-end tests)
• O-chaos (found by chaos tests)

Area:

• A-metasrv
• A-storage
• A-observability
• A-compaction
• A-distributed-write
• A-distributed-query
• A-write
• A-query
• A-flow
• A-index
• A-metric-engine
• A-wal
• A-region-autopilot
• A-frontend

Category:

• C-bug
• C-user-experience
• C-enhancement
• C-feature
• C-performance

Implementation challenges

No response

[tisonkun]

What do you think? cc @GreptimeTeam/db-approver

I'd correspondingly update the label, the automation, and issue templates.

[evenyag]

Looks good.

[tisonkun]

@evenyag Thanks for your review. For follow-ups label, I create #3855 for further discussion. The current solution is mixed, brittle and actually already has some edge cases.

[fengjiachun]

Looks great!

[tisonkun]

Thanks for your feedback. I'll apply the changes before tomorrow.