9514: Reduce Java allocations when sending internal node hashes during reconnect

[artemananiev]

Fix summary:

• getChildHashes() method in TeacherTreeView is replaced with another method, writeChildHashes(). This new method is expected to write child hashes to the specified output stream in binary format, identical to how list of Hash objects was previously written
• In StandardTeacherTreeView this method is implemented using the old getChildHashes() and serializing them with SerializableDataOutputStream.writeSerializableList()
• In VirtualTeacherTreeView this new method delegates to the underlying data source
• In VirtualDataSource a new method is added for this purpose, loadAndWriteHash()
• This new method in MerkleDbDataSource loads hash bytes from disk and serializes them to the output stream, bypassing deserialization to Hash

Testing:

• Existing virtual map reconnect tests in swirlds-merkle are used
• I found that these tests use MerkleDb, but the data source is not actually used, all nodes are loaded from virtual node cache. Fixed that
• Then I had to set hashes RAM to disk threshold to 0 to load hashes from disk, not from data source cache
• Then I found that one of the reconnect tests take 5 mins to complete because of recent async timeout update. Changed the test to use custom timeout (5s)

Fixes: #9514
Signed-off-by: Artem Ananev artem.ananev@swirldslabs.com

[github-actions]

Node: Unit Test Results

    2 259 files      2 259 suites   1h 27m 28s ⏱️
118 232 tests 118 198 ✔️ 34 💤 0 ❌
126 491 runs  126 457 ✔️ 34 💤 0 ❌

Results for commit 9890754.

♻️ This comment has been updated with latest results.

[github-actions]

Node: E2E Test Results

    1 files      1 suites   20m 32s ⏱️
310 tests 310 ✔️ 0 💤 0 ❌
332 runs  332 ✔️ 0 💤 0 ❌

Results for commit 9890754.

♻️ This comment has been updated with latest results.

[github-actions]

Node: Integration Test Results

280 tests   280 ✔️  32m 0s ⏱️
    5 suites      0 💤
    5 files        0 ❌

Results for commit 9890754.

♻️ This comment has been updated with latest results.

[github-actions]

Node: HAPI Test Results

1 228 tests   748 ✔️  1h 15m 34s ⏱️
   165 suites  480 💤
   165 files        0 ❌

Results for commit 9890754.

♻️ This comment has been updated with latest results.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (276a5e1) 65.22% compared to head (6a2fd59) 0.00%.
Report is 17 commits behind head on develop.

❗ Current head 6a2fd59 differs from pull request most recent head 9890754. Consider uploading reports for the commit 9890754 to get more accurate results

Additional details and impacted files

@@              Coverage Diff              @@
##             develop   #9538       +/-   ##
=============================================
- Coverage      65.22%       0   -65.23%     
=============================================
  Files           3257       0     -3257     
  Lines         123995       0   -123995     
  Branches       12812       0    -12812     
=============================================
- Hits           80881       0    -80881     
+ Misses         40062       0    -40062     
+ Partials        3052       0     -3052     

see 3257 files with indirect coverage changes

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