Fix: #473 changed default arg value for show_result and caused --show broke during testing

[haotian-liu]

In #473, it changed the default arg value of mmdet3d.core.visualizer.show_result, from show=True to show=False, which caused code mmdet3d.models.detectors.{mvx_two_stage/base}.show_results to broke (not showing the visualization even when --show is enabled during testing.

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[codecov]

Codecov Report

Merging #515 (66edf10) into master (b255d16) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #515   +/-   ##
=======================================
  Coverage   50.66%   50.66%           
=======================================
  Files         189      189           
  Lines       14455    14455           
  Branches     2366     2366           
=======================================
  Hits         7324     7324           
  Misses       6638     6638           
  Partials      493      493           

Flag	Coverage Δ
unittests	50.66% <ø> (ø)

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Impacted Files	Coverage Δ
mmdet3d/core/visualizer/show_result.py	64.34% <ø> (ø)

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[OpenMMLab-Coodinator]

Hi @haotian-liu ！First of all, we want to express our gratitude for your significant PR in this project. Your contribution is highly appreciated, and we are grateful for your efforts in helping improve this open-source project during your personal time. We believe that many developers will benefit from your PR.

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