fix: don't enable jemalloc by default

[DaniPopes]

It's not very portable, so we shouldn't enable it by default.

We instruct users to pass the feature when building from source for better performance (https://paradigmxyz.github.io/reth/installation/source.html), and we pass it ourselves in Makefile FEATURES

reth/Makefile

Line 18 in 5cb0258

FEATURES ?= jemalloc asm-keccak

Fixes #6742

[shekhirin]

Can't we just gate it only for supported targets from https://github.com/gnzlbg/jemallocator instead?

[gakonst]

I'd like to have it on where possible in a smarter way, yeah, can't we use this table as a guide? https://github.com/gnzlbg/jemallocator?tab=readme-ov-file#platform-support

[Rjected]

I'd like to have it on where possible in a smarter way, yeah, can't we use this table as a guide? https://github.com/gnzlbg/jemallocator?tab=readme-ov-file#platform-support

note: we might want to switch the names of the deps to tikv-* to make it more clear that we're pulling from
https://github.com/tikv/jemallocator

The crate is linked to the tikv version

[rkrasiuk]

supportive of @shekhirin & @gakonst comments, let's enable when possible

[DaniPopes]

How would you even "gate it only for supported targets" in this context? We filter the feature out in make, but you can't do this in Cargo for features.
Also to note that the target may be supported but not all systems will have the same page size set at compile time in jemalloc, which is what prompted this PR, see linked issue.

[Rjected]

It kind of sucks that jemalloc is not portable, and is causing us to make it non default, it's otherwise very good. But I guess we'll just have to pass --features "jemalloc" everywhere when using cargo cmds

Looking at the original jemalloc issue, it might be possible to have jemallocator build with --with-lg-page=16 or 64

[Rjected]

actually, it looks like an environment variable can be set
https://github.com/tikv/jemallocator/blob/af6e6529c087dc1d0ac159372111a859031269f6/jemalloc-sys/README.md?plain=1#L112

[DaniPopes]

Superseded by #7123