Bug 40651: Fix Gradle not found in GV/merge_aars

Geckoview builds were failing because the merge_aars phase was missing
Gradle. Since #40640 we are passing gradle as an argument while setting
the compiler up, but the merge_aars phase was missing it.

projects/geckoview/config

@@ -35,7 +35,10 @@ steps:
     merge_aars: |
       #!/bin/bash
       [% c("var/set_default_env") -%]
-      [% pc(c('var/compiler'), 'var/setup', { compiler_tarfile => c('input_files_by_name/' _ c('var/compiler')) }) %]
+      [% pc(c('var/compiler'), 'var/setup', {
+          compiler_tarfile => c('input_files_by_name/' _ c('var/compiler')),
+          gradle_tarfile => c("input_files_by_name/gradle"),
+        }) %]
       distdir=/var/tmp/dist
       builddir=/var/tmp/build
       mkdir -p /var/tmp/build