amend test user cleanup list (#1724)

## Type of change

- [x] 💻 CI/Deployment

## Test Plan

- [x] 💚 E2E

.github/workflows/ci_test_cleanup.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         folder: [Corso_Restore_, TestRestore, '']
-        user: [CORSO_M365_TEST_USER_ID, CORSO_SECONDARY_M365_TEST_USER_ID]
+        user: [CORSO_M365_TEST_USER_ID, CORSO_SECONDARY_M365_TEST_USER_ID, EXT_SDK_TEST_USER_ID]
 
     steps:
       - uses: actions/checkout@v3

.github/workflows/load_test.yml

@@ -61,6 +61,7 @@ jobs:
           CORSO_PASSPHRASE: ${{ secrets.CORSO_PASSPHRASE }}
           CORSO_M365_LOAD_TEST_USER_ID: ${{ secrets.CORSO_M365_LOAD_TEST_USER_ID }}
           CORSO_M365_LOAD_TEST_ORG_USERS: ${{ secrets.CORSO_M365_LOAD_TEST_ORG_USERS }}
+          IGNORE_LOAD_TEST_USER_ID: ${{ secrets.EXT_SDK_TEST_USER_ID }}
           CORSO_LOAD_TESTS: true 
         run: |
           set -euo pipefail

src/internal/tester/resource_owners.go

@@ -1,6 +1,7 @@
 package tester
 
 import (
+	"os"
 	"strings"
 	"testing"
 
@@ -89,7 +90,25 @@ func LoadTestM365OrgUsers(t *testing.T) []string {
 	users = strings.ReplaceAll(users, `'`, "")
 	users = strings.ReplaceAll(users, "|", ",")
 
-	return strings.Split(users, ",")
+	// a hack to skip using certain users when those accounts are
+	// temporarily being co-opted for non-testing purposes.
+	sl := strings.Split(users, ",")
+	remove := os.Getenv("IGNORE_LOAD_TEST_USER_ID")
+
+	if len(remove) == 0 {
+		return sl
+	}
+
+	idx := -1
+
+	for i, s := range sl {
+		if s == remove {
+			idx = i
+			break
+		}
+	}
+
+	return append(sl[:idx], sl[idx+1:]...)
 }
 
 // M365SiteID returns a siteID string representing the m365SiteID described