Replace system allocator with mimalloc

[MartinquaXD]

Description

I looked more into the supposed memory leak and noticed that the system allocator requires unreasonable amounts of memory compared to mimalloc so I replaced it for all the binaries.

Here we can see the memory footprint of the api pod with mimalloc (green) and the system allocator (yellow). The served traffic is the same but the system allocator continues to require more and more memory - probably because it's worse at dealing with memory fragmentation than mimalloc.

[squadgazzz]

Nice. When I was testing this initially, it didn't help at all since the memory growth wasn't so massive. Basically, this brings us back to the slow memory leak. Interesting, what exactly has increased the memory consumption lately.

[MartinquaXD]

Interesting, what exactly has increased the memory consumption lately.

The first time this crazy memory usage happened was after merging #2996 but that does not contain any changes relevant to the API pod. :/
And for prod the issues started with release https://github.com/cowprotocol/services/releases/tag/v2.279.0 which also doesn't contain any significant code changes for the api pod. That release also merged the new deployement code but I don't expect that to have any influence either.

The only reasonable explanation that currently comes to mind is that the system memory allocator might have gotten replaced but I couldn't find good information on that. 🤷‍♂️

[mstrug]

@MartinquaXD did you considered also jemalloc or tcmalloc?
There is some benchmarks that shows both of them are using less memory than mimalloc:
https://lf-hyperledger.atlassian.net/wiki/spaces/BESU/pages/22156632/Reduce+Memory+usage+by+choosing+a+different+low+level+allocator
Also other project was checking if replacing currently used jemalloc by mimalloc will gain performance to their project and most of the benchmark were worse: ClickHouse/ClickHouse#59497
Probably this depends on the particular project, so it would be good to have some benchmarks on our code which we can compare on different allocator.