github-actions: Only run production suite on production related updates.

The production suite will only run if anything under puppet,
scripts, and tools or any migrations are updated. The '**' glob
means it includes subdirectory updates. For migrations all ~5
migrations directories are includes using the **/migrations/**
pattern.

The GitHub Action docs that explain the syntax:
https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#filter-pattern-cheat-sheet

.github/workflows/production-suite.yml

@@ -2,7 +2,27 @@ name: Zulip Production Suite
 
 on:
   push:
+    paths:
+      - "**/migrations/**"
+      - puppet/**
+      - requirements/**
+      - scripts/**
+      - static/**
+      - tools/**
+      - zproject/**
+      - yarn.lock
+      - .github/workflows/production-suite.yml
   pull_request:
+    paths:
+      - "**/migrations/**"
+      - puppet/**
+      - requirements/**
+      - scripts/**
+      - static/**
+      - tools/**
+      - zproject/**
+      - yarn.lock
+      - .github/workflows/production-suite.yml
 
 defaults:
   run: