chore: update environment name in workflow and switch to vars for JIRA_BASE_URL

Author: jirhiker

.github/workflows/jira_codex_pr.yml

@@ -37,8 +37,8 @@ env:
 jobs:
   implement:
     runs-on: ubuntu-latest
-    timeout-minutes: 60
     environment: jira-codex
+    timeout-minutes: 60
     steps:
       - name: Checkout
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4