Linearize function ids

[vchuravy]

Some tools (parca) expect function ids to increment linearly

[vchuravy]

Example of a parca config to be used with ProfileEndpoints.jl

scrape_configs:
  - job_name: "parca"
    scrape_interval: "10s"
    scrape_timeout: "60s"
    static_configs:
      - targets: [ '127.0.0.1:16825' ]
    profiling_config:
      pprof_config:
        julia:
          enabled: true
          path: '/profile'
          delta: true