[MM-61074] Fix errcheck issues in oauth_test.go and web_test.go (#30707)

Co-authored-by: Claude <noreply@anthropic.com>

server/channels/jobs/export_delete_test.go

@@ -36,7 +36,6 @@ func TestExportDelete(t *testing.T) {
 	}
 
 	th := SetupWithUpdateCfg(t, updateConfig)
-	defer th.TearDown()
 
 	// Create test files with different timestamps
 	files := []string{