fix: Data table z index in sql Editor (#13972)

(cherry picked from commit 7fb138381fd7a281735f913333abe9a5a5da2349)
diff --git a/superset-frontend/src/SqlLab/main.less b/superset-frontend/src/SqlLab/main.less
index 0b79b86..d262ef8 100644
--- a/superset-frontend/src/SqlLab/main.less
+++ b/superset-frontend/src/SqlLab/main.less
@@ -300,7 +300,7 @@
   .schemaPane-enter-done,
   .schemaPane-exit {
     transform: translateX(0);
-    z-index: 1020;
+    z-index: 7;
   }
 
   .schemaPane-exit-active {