refactor: made placeholder text a bit lighter

Author: devvaannsh

src/styles/Extn-CustomSnippets.less

@@ -470,9 +470,11 @@
 
             &::-webkit-input-placeholder {
                 color: @bc-text-thin-quiet;
+                opacity: 0.6;
 
                 .dark & {
                     color: @dark-bc-text-thin-quiet;
+                    opacity: 0.7;
                 }
             }