chore: remove manual_test_memory_client.py

[Hweinstock]

Issue #, if available: #316

Description of changes:

• delete unused testing file.
• This file is made obsolete by https://github.com/aws/bedrock-agentcore-sdk-python/blob/main/tests_integ/memory/test_memory_client.py.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@51e26c7). Learn more about missing BASE report.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #337   +/-   ##
=======================================
  Coverage        ?   90.90%           
=======================================
  Files           ?       43           
  Lines           ?     4068           
  Branches        ?      624           
=======================================
  Hits            ?     3698           
  Misses          ?      203           
  Partials        ?      167           

Flag	Coverage Δ
unittests	90.90% <ø> (?)

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