chore: rename converged_infra tag to platform_engineering (#507)

Co-authored-by: Harika-Ponna <Harika.Ponna@ibm.com>

Author: HarikaPonna

ibm_catalog.json

@@ -10,7 +10,7 @@
         "terraform",
         "solution",
         "network",
-        "converged_infra"
+        "platform_engineering"
       ],
       "keywords": [
         "IaC",