Improve performance of the redis get command avoiding fiber switches for small set of data

[danielealbano]

This PR fixes an optimisation that was broken in PR #99, it ensure that if the data to read from the storage are smaller than 64kb - 32 bytes everything gets sent without switching fiber context, dramatically reducing the latency.

The PR also include a non related fix that sets the build optimisation level to 2 as it's the one normally used for the packages in the distro.

[codecov]

Codecov Report

Merging #123 (c20a3b1) into main (e75865d) will decrease coverage by 0.50%.
The diff coverage is 41.50%.

@@            Coverage Diff             @@
##             main     #123      +/-   ##
==========================================
- Coverage   78.93%   78.42%   -0.51%     
==========================================
  Files          86       86              
  Lines        5041     5043       +2     
==========================================
- Hits         3979     3955      -24     
- Misses       1062     1088      +26     

Impacted Files	Coverage Δ
...redis/command/network_protocol_redis_command_get.c	52.79% <31.11%> (-11.36%)	⬇️
src/protocol/redis/protocol_redis_reader.c	92.64% <100.00%> (ø)
src/slab_allocator.c	92.69% <0.00%> (-3.08%)	⬇️
src/spinlock.c	100.00% <0.00%> (+2.43%)	⬆️

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