[git-svn] fix Duplicate specification "id|i=s" for option "i" - #2381

The `-i` parameter is defined 2 times:
  - `--id`
  - `--interactive`

what causes warning `Duplicate specification "id|i=s" for option "i"` by Getopt::Long 2.58
To fix this remove `-i` for `--interactive`


https://github.com/git/git/blob/master/git-svn.perl#L199
```
	dcommit => [ \&cmd_dcommit,
	             'Commit several diffs to merge with upstream',
			{ 'merge|m|M' => \$_merge,
			  'strategy|s=s' => \$_strategy,
			  'verbose|v' => \$_verbose,
			  'dry-run|n' => \$_dry_run,
			  'fetch-all|all' => \$_fetch_all,
			  'commit-url=s' => \$_commit_url,
			  'set-svn-props=s' => \$_set_svn_props,
			  'revision|r=i' => \$_revision,
			  'no-rebase' => \$_no_rebase,
			  'mergeinfo=s' => \$_merge_info,
>>>>		  'interactive|i' => \$_interactive,
			%cmt_opts, %fc_opts } ],
```

```
https://github.com/git/git/blob/master/git-svn.perl#L350
my $rv = GetOptions(%opts, 'h|H' => \$_help, 'version|V' => \$_version,
                    'minimize-connections' => \$Git::SVN::Migration::_minimize,
>>>>                'id|i=s' => \$Git::SVN::default_ref_id,
                    'svn-remote|remote|R=s' => sub {
                       $Git::SVN::no_reuse_existing = 1;
                       $Git::SVN::default_repo_id = $_[1] });
```