fix: remove default registry definition in Dockerfile.

[Komey]

Ⅰ. Describe what this PR did

fix: remove default registry definition in Dockerfile.
fix: change dfpath default value in dfdaemon config template.

Ⅱ. Does this pull request fix one issue?

Ⅲ. Why don't you add test cases (unit test/integration test)? (你真的觉得不需要加测试吗？)

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

1. CLI的参数优先级大于配置文件的，官方镜像带了--registry参数， 导致使用的时候 必须手动覆盖掉
2. 修改配置文件的文档错误

[codecov-commenter]

Codecov Report

Merging #1385 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1385      +/-   ##
==========================================
- Coverage   51.77%   51.76%   -0.02%     
==========================================
  Files         137      137              
  Lines        9078     9078              
==========================================
- Hits         4700     4699       -1     
  Misses       3995     3995              
- Partials      383      384       +1     

Impacted Files	Coverage Δ
supernode/daemon/mgr/scheduler/manager.go	21.91% <0.00%> (-0.69%)	⬇️

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[lowzj]

LGTM

[zhouhaibing089]

LGTM