speed up the docker build

[wyTrivail]

Description:

Speed up the docker build,

1. use go mod download to cache the downloading libs.
2. just build amd64 binary in docker.

Testing:

Manually tested. reduce the time from 25 minutes to 14 minutes

[codecov-io]

Codecov Report

Merging #93 into main will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #93   +/-   ##
=======================================
  Coverage   75.71%   75.71%           
=======================================
  Files           4        4           
  Lines          70       70           
=======================================
  Hits           53       53           
  Misses          9        9           
  Partials        8        8           

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