versioninfo() reports confusing number of threads on master

[Seelengrab]

[sukera@tower julia]$ julia -qt 10,1
julia> versioninfo()
Julia Version 1.10.0-DEV.1287
Commit c6fc12c9ee (2023-05-12 14:02 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: 24 × AMD Ryzen 9 7900X 12-Core Processor
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-15.0.7 (ORCJIT, znver3)
  Threads: 15 on 24 virtual cores

10 threads for the :default threadpool are requested, as well as one for the :interactive threadpool, but versioninfo() reports 15. As far as I can tell, that's due to

--gcthreads=N             Use N threads for GC, set to half of the number of compute threads if unspecified.

introduced in #48600. Not sure how to best query that new information yet, but printing something like Threads: 10 compute, 1 interactive, 5 GC on 24 virtual cores might be nice.

[jmkuhn]

Duplicate of #49753