Stop using centos image for bloat check

The bloat check started failing after the checkout action started
to require nodejs 20 (See actions/checkout#1590).
By changing the image the bloat check should still provide enough
insight into binary size at the expense of the binaries being
slightly different from a production build.

.github/workflows/bloat.yaml

@@ -25,7 +25,7 @@ jobs:
       contents: read
 
     container:
-      image: ghcr.io/gravitational/teleport-buildbox-centos7:teleport14
+      image: ghcr.io/gravitational/teleport-buildbox:teleport14
 
     steps:
       - name: Checkout base