[cleanup][txn] Use MLTransactionMetadataStore in integration tests

[nicoloboschi]

Motivation

Transaction's integration tests use the in memory implementation for the txn metadata store.
Since they're very important test to ensure stability of the transactions feature, it's better to use the default store which is actually designed to run in production environments.

Modifications

• Do not set InMemTransactionMetadataStoreProvider in the integration tests setup

Documentation

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

[codelipenghui]

/pulsarbot run-failure-checks

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 47.32%. Comparing base (4b8f447) to head (f8e48e1).
⚠️ Report is 3035 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #19140      +/-   ##
============================================
+ Coverage     47.00%   47.32%   +0.32%     
- Complexity    10639    10731      +92     
============================================
  Files           713      713              
  Lines         69672    69672              
  Branches       7482     7482              
============================================
+ Hits          32746    32973     +227     
+ Misses        33212    33009     -203     
+ Partials       3714     3690      -24     

Flag	Coverage Δ
unittests	47.32% <ø> (+0.32%)	⬆️

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see 48 files with indirect coverage changes

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