RuboCop: Fix offenses for Performance/MethodObjectAsBlock

What does this MR do and why?

This MR fixes offenses for 👮 Performance/MethodObjectAsBlock (part 1 of 2) manually.

How to set up and validate locally

bundle exec rubocop --only Performance/MethodObjectAsBlock --parallel

Benchmark

From https://github.com/fastruby/fast-ruby#normal-way-to-apply-method-vs-method-code

Using &method(...) is ~2.5x slower than { ... }.

Click to expand

# frozen_string_literal: true

require "benchmark/ips"

def do_something(n)
    4*n + 2
end

def fast
    [1, 2, 3].map { |n| do_something(n) }
end

def slow
    [1, 2, 3].map(&method(:do_something))
end

Benchmark.ips do |x|
  x.report("normal")  { fast }
  x.report("&method") { slow }
  x.compare!
end

Warming up --------------------------------------
              normal   397.640k i/100ms
             &method   171.679k i/100ms
Calculating -------------------------------------
              normal      3.550M (±21.7%) i/s -     17.099M in   5.098570s
             &method      1.426M (± 8.5%) i/s -      7.211M in   5.098390s

Comparison:
              normal:  3549722.4 i/s
             &method:  1425508.8 i/s - 2.49x  (± 0.00) slower

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.