[fuchsia] Prepare builder bot rename

Bug: chromium:1033865
Change-Id: Id20517aa4a8a0bbc6e9cf593ce29504f16297e5d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2017473Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Liviu Rau <liviurau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65971}

infra/mb/mb_config.pyl

@@ -92,6 +92,8 @@
           'release_simulate_arm64_pointer_compression',
       'V8 Fuchsia': 'release_x64_fuchsia',
       'V8 Fuchsia - debug': 'debug_x64_fuchsia',
+      'V8 Fuchsia - builder': 'release_x64_fuchsia',
+      'V8 Fuchsia - debug builder': 'debug_x64_fuchsia',
       'V8 Linux64 - cfi': 'release_x64_cfi',
       'V8 Linux64 UBSan': 'release_x64_ubsan',
       'V8 Linux - vtunejit': 'debug_x86_vtunejit',