content/static: remove icon next to source files

Removes icons from source files and adjusts
spacing of the grid for better readability.

Change-Id: I7ef7c8fc19dd641652219321f113862277be0830
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/260728
Trust: Jamal Carvalho <[email protected]>
Run-TryBot: Jamal Carvalho <[email protected]>
TryBot-Result: kokoro <[email protected]>
Reviewed-by: Julie Qiu <[email protected]>

Author: jamalc

content/static/css/unit_files.css

@@ -29,7 +29,7 @@
 }
 .UnitFiles-fileList {
   display: grid;
-  grid-template-columns: repeat(auto-fill, minmax(12rem, 1fr));
+  grid-template-columns: repeat(auto-fill, minmax(10.5rem, auto));
   line-height: 1.5rem;
   list-style: none;
   padding-left: 0;
@@ -41,7 +41,3 @@
   text-overflow: ellipsis;
   white-space: nowrap;
 }
-.UnitFiles-file::before {
-  content: url(/static/img/pkg-icon-file_16x12.svg);
-  margin-right: 0.75rem;
-}