Add AWS IAM integration tests and refactor admin authorization (#8098)

* Add AWS IAM integration tests and refactor admin authorization
- Added AWS IAM management integration tests (User, AccessKey, Policy)
- Updated test framework to support IAM client creation with JWT/OIDC
- Refactored s3api authorization to be policy-driven for IAM actions
- Removed hardcoded role name checks for admin privileges
- Added new tests to GitHub Actions basic test matrix

* test(s3/iam): add UpdateUser and UpdateAccessKey tests and fix nil pointer dereference

* feat(s3api): add DeletePolicy and update tests with cleanup logic

* test(s3/iam): use t.Cleanup for managed policy deletion in CreatePolicy test

test/s3/iam/iam_config.json

@@ -230,10 +230,12 @@
           {
             "Effect": "Allow",
             "Action": [
-              "s3:*"
+              "s3:*",
+              "iam:*"
             ],
             "Resource": [
-              "*"
+              "*",
+              "arn:aws:iam:::*"
             ]
           },
           {
@@ -342,4 +344,4 @@
       }
     }
   ]
-}
+}