Update Soy templates to use the ! operator instead of 'not'.

A small step towards converging Soy with TypeScript syntax.

Test: bazel test //...
Test: verified that `bazel test //...` fails without parent commit to update Soy version
Change-Id: I82189b043aca357f2562d77e83526815e3183d75

resources/com/google/gitiles/templates/HostIndex.soy

diff --git a/resources/com/google/gitiles/templates/HostIndex.soy b/resources/com/google/gitiles/templates/HostIndex.soy
index 846904a..353fd4f 100644
--- a/resources/com/google/gitiles/templates/HostIndex.soy
+++ b/resources/com/google/gitiles/templates/HostIndex.soy
@@ -34,7 +34,7 @@
 {/call}
 
 {if length($repositories)}
-  {if not $breadcrumbs}
+  {if !$breadcrumbs}
     <h1>
       {msg desc="Git repositories available on the host"}
         Git repositories on {$hostName}