chore(deps): upgrade nginx-lua-prometheus to 0.20220527

[tkan145]

What

Bump nginx-lua-prometheus to 0.20220527.

Due to the library change, it's now requires to call init_worker, we need to refactor a bit of code as well.

Verification steps

• Checkout this branch
• Build new runtime image

make runtime-image IMAGE_NAME=apicast-test

• Get inside dev env

cd dev-environments/plain-http-upstream

• Update docker-compose.yaml as follow

diff --git a/dev-environments/plain-http-upstream/docker-compose.yml b/dev-environments/plain-http-upstream/docker-compose.yml
index ebf84ebc..ff120b35 100644
--- a/dev-environments/plain-http-upstream/docker-compose.yml
+++ b/dev-environments/plain-http-upstream/docker-compose.yml
@@ -18,9 +18,11 @@ services:
     expose:
       - "8080"
       - "8090"
+      - "9421"
     ports:
       - "8080:8080"
       - "8090:8090"
+      - "9421:9421"
     volumes:
       - ./apicast-config.json:/tmp/config.json
   example.com:

• Send request to query metrics

curl --resolve get.example.com:9421:127.0.0.1 -v "http://get.example.com:9421/metrics"

You should see metrics response.