This reverts commit 6b084326.

Reason for revert: creates CLs that are on top of stale commits, not ToT

Original change's description:
> Use main as default branch for git recipe module
>
> R=​apolito@google.com, ehmaldonado@chromium.org
>
> Recipe-Nontrivial-Roll: build_limited_scripts_slave
> Recipe-Nontrivial-Roll: chromiumos
> Recipe-Nontrivial-Roll: infra
> Change-Id: Ia0d39ae574852fa008a55e366c2320eb1845dc86
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2941678
> Commit-Queue: Josip Sokcevic <sokcevic@google.com>
> Reviewed-by: Anthony Polito <apolito@google.com>

Change-Id: I64ed8e7fbeab8cf8a0be6be4456fee400f770883
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2998588
Auto-Submit: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>