completions: improve list of available services and outdated checks

[razvanazamfirei]

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This PR makes some improvements to the completions.

1. It improves the logic for finding services
2. It passes HOMEBREW_NO_AUTO_UPDATE=1 to all brew outdated calls in the completions. While this change prevents the completion from fetching outdated casks/formulas by itself, it represents a substantial improvement in a completion that is otherwise input-blocking.

❯ hyperfine "brew outdated --formula --verbose  | string replace -r '\s' '\t'" "HOMEBREW_NO_AUTO_UPDATE=1 brew outdated --formula --verbose 2>/dev/null | string replace -r '\s' '\t'" --shell fish
Benchmark 1: brew outdated --formula --verbose  | string replace -r '\s' '\t'
  Time (mean ± σ):      3.686 s ±  0.879 s    [User: 0.845 s, System: 0.238 s]
  Range (min … max):    3.183 s …  6.048 s    10 runs

Benchmark 2: HOMEBREW_NO_AUTO_UPDATE=1 brew outdated --formula --verbose 2>/dev/null | string replace -r '\s' '\t'
  Time (mean ± σ):      1.462 s ±  0.045 s    [User: 0.836 s, System: 0.223 s]
  Range (min … max):    1.399 s …  1.548 s    10 runs

Summary
  HOMEBREW_NO_AUTO_UPDATE=1 brew outdated --formula --verbose 2>/dev/null | string replace -r '\s' '\t' ran
    3.52 ± 0.61 times faster than brew outdated --formula --verbose  | string replace -r '\s' '\t'

❯ hyperfine "brew outdated --cask --verbose 2>/dev/null | string replace -r '\s' '\t'" "HOMEBREW_NO_AUTO_UPDATE=1 brew outdated --cask --verbose 2>/dev/null | string replace -r '\s' '\t'" --shell fish
Benchmark 1: brew outdated --cask --verbose 2>/dev/null | string replace -r '\s' '\t'
  Time (mean ± σ):      3.211 s ±  0.013 s    [User: 0.454 s, System: 0.140 s]
  Range (min … max):    3.190 s …  3.232 s    10 runs

Benchmark 2: HOMEBREW_NO_AUTO_UPDATE=1 brew outdated --cask --verbose 2>/dev/null | string replace -r '\s' '\t'
  Time (mean ± σ):     886.5 ms ±  68.7 ms    [User: 433.1 ms, System: 125.2 ms]
  Range (min … max):   812.5 ms … 1018.8 ms    10 runs

Summary
  HOMEBREW_NO_AUTO_UPDATE=1 brew outdated --cask --verbose 2>/dev/null | string replace -r '\s' '\t' ran
    3.62 ± 0.28 times faster than brew outdated --cask --verbose 2>/dev/null | string replace -r '\s' '\t'

Benchmark 1:     command find (brew --cellar) -mindepth 3 -maxdepth 3 -name '*.service'       | awk -F'homebrew.|.service' '{print }'       | sort -d
  Time (mean ± σ):      59.2 ms ±   3.3 ms    [User: 8.4 ms, System: 43.4 ms]
  Range (min … max):    56.1 ms …  73.2 ms    27 runs

Benchmark 2:     set -l list (brew services list)
    set -e list[1] # Header
    for line in
        echo (string split ' ' )[1]
    end
  Time (mean ± σ):      1.687 s ±  0.097 s    [User: 0.861 s, System: 0.305 s]
  Range (min … max):    1.589 s …  1.933 s    10 runs

Summary
      command find (brew --cellar) -mindepth 3 -maxdepth 3 -name '*.service'       | awk -F'homebrew.|.service' '{print }'       | sort -d ran
   28.48 ± 2.29 times faster than     set -l list (brew services list)
    set -e list[1] # Header
    for line in
        echo (string split ' ' )[1]
    end

[MikeMcQuaid]

Great idea, thanks @razvanazamfirei!