[2.6] MOD-5904: Fix DocTable memsize (#5099)

[nafraf]

Description

Manual backport of #5099 to 2.6.
(cherry picked from commit b4234ed)

Adjustments for 2.6

• 2.6 does not contain tests/cpptests/test_cpp_llapi.cpp: TEST_F(LLApiTest, testInfoSizeWithExistingIndex)
• sizeof(DocTable) = 64 bytes, because does not contain TimeToLiveTable* ttl;
• TEST_F(LLApiTest, testInfoSize) was modified because 2.6 does not contain the changes to count numeric range tree overhead

[codecov]

Codecov Report

Attention: Patch coverage is 57.14286% with 3 lines in your changes missing coverage. Please review.

Project coverage is 85.17%. Comparing base (a19d287) to head (ad20abf).
Report is 2 commits behind head on 2.6.

Files with missing lines	Patch %	Lines
src/doc_table.c	57.14%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              2.6    #5816      +/-   ##
==========================================
- Coverage   85.18%   85.17%   -0.01%     
==========================================
  Files         185      185              
  Lines       31500    31507       +7     
==========================================
+ Hits        26832    26837       +5     
- Misses       4668     4670       +2     

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