Revert "Add padding around flutter api docs search input (#44980)" (#63113)

This reverts commit c8cb245f24caa8c38ae4d6241010690d0b534b02.
diff --git a/dev/docs/assets/overrides.css b/dev/docs/assets/overrides.css
index 26ad632..74b249f 100644
--- a/dev/docs/assets/overrides.css
+++ b/dev/docs/assets/overrides.css
@@ -107,7 +107,7 @@
   background-image: none;
   border: 1px solid #ccc;
   border-radius: 2px;
-  padding: 14px 6px;
+  padding: 4px 6px;
   font-size: 15px;
 }