[fix][cli] Fix output of --print-metadata in cli consume

[lhotari]

Motivation

Appending a bytes array to a StringBuilder doesn't make sense. Code was added in #23347.
This issue found with errorprone.

Modifications

• fix issue by calling encodeToString on Base64 encoder

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.33%. Comparing base (89f6015) to head (395223e).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
...g/apache/pulsar/client/cli/AbstractCmdConsume.java	0.00%	2 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             master   #25056       +/-   ##
=============================================
+ Coverage     38.64%   74.33%   +35.68%     
- Complexity    13341    34111    +20770     
=============================================
  Files          1864     1921       +57     
  Lines        146223   150387     +4164     
  Branches      16984    17470      +486     
=============================================
+ Hits          56506   111784    +55278     
+ Misses        82051    29689    -52362     
- Partials       7666     8914     +1248     

Flag	Coverage Δ
inttests	26.37% <0.00%> (-0.07%)	⬇️
systests	22.85% <0.00%> (-0.04%)	⬇️
unittests	73.87% <0.00%> (+39.05%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...g/apache/pulsar/client/cli/AbstractCmdConsume.java	16.39% <0.00%> (+16.39%)	⬆️

... and 1421 files with indirect coverage changes

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