Remove deprecated MediaManager

[vinnamkim]

Summary

• Ticket no. 131646
• MediaManager looks deprecated because there is no usage (.get()) in the codebase but only remains .push() and .clear().
• However, this makes weakref-related errors in OTX 2.0 integration tests. Therefore, it seems good to remove.

How to test

No need for the test

Checklist

• I have added unit tests to cover my changes.​
• I have added integration tests to cover my changes.​
• I have added the description of my changes into CHANGELOG.​
• I have updated the documentation accordingly

License

• I submit my code changes under the same MIT License that covers the project.
  Feel free to contact the maintainers if that's a concern.
• I have updated the license header for each file (see an example below).

# Copyright (C) 2023 Intel Corporation
#
# SPDX-License-Identifier: MIT

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (784e039) 80.54% compared to head (4f34d64) 80.55%.
Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1262   +/-   ##
========================================
  Coverage    80.54%   80.55%           
========================================
  Files          271      270    -1     
  Lines        30438    30406   -32     
  Branches      5930     5925    -5     
========================================
- Hits         24517    24493   -24     
+ Misses        4532     4525    -7     
+ Partials      1389     1388    -1     

Flag	Coverage Δ
ubuntu-20.04_Python-3.8	80.54% <100.00%> (+<0.01%)	⬆️
windows-2022_Python-3.8	80.52% <100.00%> (+<0.01%)	⬆️

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[wonjuleee]

LGTM