fix: discard tagging output when pushing with formatted output

[qweeah]

What this PR does / why we need it:
This PR discards the tagging output of oras push to avoid corrupting formatted output

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #1300

Please check the following list:

• Does the affected code have corresponding tests, e.g. unit test, E2E test?
• Does this change require a documentation update?
• Does this introduce breaking changes that would require an announcement or bumping the major version?
• Do all new files have an appropriate license header?

[codecov]

Codecov Report

Attention: Patch coverage is 89.23077% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 84.53%. Comparing base (61557e0) to head (03135a9).

Files	Patch %	Lines
internal/listener/tag.go	83.33%	2 Missing and 2 partials ⚠️
cmd/oras/internal/display/metadata/json/push.go	0.00%	2 Missing ⚠️
cmd/oras/root/push.go	75.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1302      +/-   ##
==========================================
+ Coverage   84.49%   84.53%   +0.04%     
==========================================
  Files         101      103       +2     
  Lines        3637     3647      +10     
==========================================
+ Hits         3073     3083      +10     
- Misses        335      336       +1     
+ Partials      229      228       -1     

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[shizhMSFT]

Tagged xxx in oras push should be metadata output instead of status output.

[shizhMSFT]

LGTM

[shizhMSFT]

LGTM