Deprecate configuration related to git_trace_log_file
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### Summary
Currently gitlab-shell no longer support actions related to git_trace_log_file.
Code related to git_trace_log_file in https://gitlab.com/gitlab-org/gitlab-shell/commit/0b4fd0af16555b2bdc28f6b18781d72226c5d56c has long gone by now.
See https://gitlab.com/gitlab-org/gitaly/issues/1300 for reference of removal commit
### Steps to reproduce
```bash
>rg git_trace_log_file
files/gitlab-config-template/gitlab.rb.template
804:# gitlab_shell['git_trace_log_file'] = "/var/log/gitlab/gitlab-shell/gitlab-shell-git-trace.log"
spec/chef/recipes/gitlab-shell_spec.rb
89: git_trace_log_file: '/tmp/log/gitlab-shell-git-trace.log'
97: git_trace_log_file: '/tmp/log/gitlab-shell-git-trace.log'
files/gitlab-cookbooks/gitlab/attributes/default.rb
448:default['gitlab']['gitlab-shell']['git_trace_log_file'] = nil
files/gitlab-cookbooks/gitlab/recipes/gitlab-shell.rb
76: git_trace_log_file: node['gitlab']['gitlab-shell']['git_trace_log_file'],
files/gitlab-cookbooks/gitlab/templates/default/gitlab-shell-config.yml.erb
43:<% if @git_trace_log_file %>
49:git_trace_log_file: "<%= @git_trace_log_file %>"
```
### What is the current *bug* behavior?
Poor documentation and confusing configuration
### What is the expected *correct* behavior?
References related to this settings should be removed together with the code in gitlab-shell
issue