## Problem
The code to generate symbolized pprof heap profiles and flamegraph SVGs
has been upstreamed to the `jemalloc_pprof` crate:
* https://github.com/polarsignals/rust-jemalloc-pprof/pull/22
* https://github.com/polarsignals/rust-jemalloc-pprof/pull/23
## Summary of changes
Use `jemalloc_pprof` to generate symbolized pprof heap profiles and
flamegraph SVGs.
This reintroduces a bunch of internal jemalloc stack frames that we'd
previously strip, e.g. each stack now always ends with
`prof_backtrace_impl` (where jemalloc takes a stack trace for heap
profiling), but that seems ok.
Avoids compiling the crate and its dependencies into binaries that don't
need them. Shrinks the compute_ctl binary from about 31MB to 28MB in the
release-line-debug-size-lto profile.
