Revert "init: change --manifest-depth default to 1"

This reverts commit 622a5bf9c2.

CrOS infra is failing to sync code now for some reason.
Until we can investigate further, pull this back out.

Bug: 475668525
Bug: 468033850
Change-Id: I35a8623a95336df1be27ea870afbfc8065609f01
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/545141
Reviewed-by: Gavin Mak <gavinmak@google.com>
Tested-by: Mike Frysinger <vapier@google.com>
Commit-Queue: Mike Frysinger <vapier@google.com>

man/repo-init.1

@@ -1,5 +1,5 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man.
-.TH REPO "1" "December 2025" "repo init" "Repo Manual"
+.TH REPO "1" "September 2024" "repo init" "Repo Manual"
 .SH NAME
 repo \- repo init - manual page for repo init
 .SH SYNOPSIS
@@ -53,7 +53,7 @@ create a git checkout of the manifest repo
 .TP
 \fB\-\-manifest\-depth\fR=\fI\,DEPTH\/\fR
 create a shallow clone of the manifest repo with given
-depth (0 for full clone); see git clone (default: 1)
+depth (0 for full clone); see git clone (default: 0)
 .SS Manifest (only) checkout options:
 .TP
 \fB\-c\fR, \fB\-\-current\-branch\fR