Revert "Activate is_offcial_build option for perf builders"

This reverts commit b3c6e1ac.

Reason for revert: The build time incresed significantly. We want to investigate if we can reduce it by removing the 'packaging' step.

Original change's description:
> Activate is_offcial_build option for perf builders
> 
> Bug: v8:9898
> Change-Id: I41e1fcb37755906e29e6937b805cfb3018e90438
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1888937
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Commit-Queue: Liviu Rau <liviurau@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#64640}

TBR=machenbach@chromium.org,tmrts@chromium.org,liviurau@chromium.org

Change-Id: Ifbae1d7aedbfb7e4f7622c5a2bec74bc2f06e7f6
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9898
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1890092Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Liviu Rau <liviurau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64645}

infra/mb/mb_config.pyl

@@ -722,7 +722,8 @@
     },
 
     'official': {
-      'gn_args': 'is_official_build=true',
+      # TODO(liviurau): switch this to true after new perf builders are in use
+      'gn_args': 'is_official_build=false',
     },
 
     'shared': {