feat: Use jemalloc everywhere instead of malloc

There may be many reasons for the discrepancy in jemalloc reported allocations total sizes and RSS.
One of them is that our binary doesn't use jmalloc for all the allocations.

Turns out that jemallocator only sets the global rust allocator. Any call to `malloc` will still
go throught the system allocator. Presumably those calls come from linked C code,
but it's also not impossible that not all rust code honours the global allocator (I have no idea, but let's see)

Cargo.toml

@@ -100,7 +100,7 @@ serde_urlencoded = "0.7.0"
 snafu = "0.6.9"
 structopt = "0.3.21"
 thiserror = "1.0.23"
-tikv-jemallocator = "0.4.0"
+tikv-jemallocator = {version = "0.4.0", features = ["unprefixed_malloc_on_supported_platforms"] }
 tikv-jemalloc-ctl = "0.4.0"
 tokio = { version = "1.0", features = ["macros", "rt-multi-thread", "parking_lot", "signal"] }
 tokio-stream = { version = "0.1.2", features = ["net"] }