chore: change the default port of manager api from 8080 to 9000

[nic-chen]

Please answer these questions before submitting a pull request

• Why submit this pull request?

• Bugfix

• New feature provided

• Improve performance

• Related issues

close #901

[codecov-io]

Codecov Report

Merging #931 (8776fae) into master (18744a5) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #931   +/-   ##
=======================================
  Coverage   42.82%   42.82%           
=======================================
  Files          18       18           
  Lines        1289     1289           
=======================================
  Hits          552      552           
  Misses        645      645           
  Partials       92       92           

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[membphis]

we can update the architecture diagram to help users understand these ports.

do this later in a new PR.