Fix: Collection dropdown chevron overlapping Import Document(s) button (#43321)

- Override Combobox grid-template-columns to minmax(0, 1fr) auto to allow
  input column to shrink below its intrinsic width, preventing chevron overflow
- Change topContainer align-items to start for consistent button alignment

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Shubhangi-Microsoft

src/ContentProcessorWeb/src/Pages/DefaultPage/Components/SchemaDropdown/SchemaDropdown.styles.scss

@@ -1,4 +1,5 @@
 .comboboxClass{
     width: 100%;
     min-width: 125px !important;
+    grid-template-columns: minmax(0, 1fr) auto !important;
 }

src/ContentProcessorWeb/src/Pages/DefaultPage/Panels.styles.scss

@@ -51,15 +51,15 @@
   .topContainer {
     display: flex;
     flex-wrap: nowrap;
-    align-items: end;
+    align-items: start;
     gap: 10px;
     padding: 0px 16px 16px 16px;
   }
 
   @media (max-width: 1600px) {
     .topContainer {
       flex-wrap: wrap;
-      align-items: center;
+      align-items: start;
     }
   }