Add test for memory leak prevention while inserting blobs

[aistis-]

Seems that every Value::blob(...) object leaves 64 bytes leftovers in the memory thus causing a memory leak. This was discovered in our PHP long-running scripts which inserts hundred of thousands records per run.

[paul-brackin]

@aistis- thanks for the PR. I am curious.. how did you come up with 1KB as being the acceptable memory loss threshold?

We will be investigating your issue soon.

[aistis-]

I did pick 1KB as this is tolerable per 10k iterarations and give a minor space for the fluctuations. However, during the testing it turned out that PHP's garbage collector did a good job and the actual memory usage delta is 0 bytes when used string instead of blob. Feel keep to change the threshold or make it 0.

Note, that the memory leak is linear: 640000 bytes per 10k iterations, 960000 bytes per 15k iterations and so on.

I was testing on PHP 8.3

[khaf]

Merged.