infra: Re-migrate linux-ozone-rel to Goma RBE

This was previously reverted due to reaching the Goma RBE server
capacity limit.
https://chromium-review.googlesource.com/c/chromium/src/+/1786872

The limit has since been increased.

R=bpastene@chromium.org, jbudorick@chromium.org, tikuta@chromium.org

Bug: 1001231,950413
Change-Id: I820be1e6128db0d6ff16c9e8d3b12207db71cf92
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1789220Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Commit-Queue: Simon Que <sque@chromium.org>
Cr-Commit-Position: refs/heads/master@{#694653}

infra/config/cr-buildbucket.cfg

@@ -1778,7 +1778,7 @@ buckets {
 
     builders {
       name: "linux-gcc-rel"
-      mixins: "linux-ci"
+      mixins: "linux-ci-goma-rbe-prod"
       mixins: "builderless"
     }
 
@@ -4488,6 +4488,7 @@ buckets {
     builders {
       mixins: "builderless"
       mixins: "linux-try"
+      mixins: "goma-rbe-prod"
       name: "linux-ozone-rel"
       mixins: "builderless"
     }

infra/config/luci-milo.cfg

@@ -3093,6 +3093,11 @@ consoles {
     category: "week2.5|linux"
     short_name: "gpu"
   }
+  builders {
+    name: "buildbucket/luci.chromium.ci/linux-ozone-rel"
+    category: "week3a|linux"
+    short_name: "ozone"
+  }
   builders {
     name: "buildbucket/luci.chromium.ci/linux-annotator-rel"
     category: "week3a|linux"