Remove "Miscellaneous checks" from CI

It is expected to use on master branch

.github/workflows/check_misc.yml

@@ -1,122 +0,0 @@
-name: Miscellaneous checks
-on: [push, pull_request]
-
-concurrency:
-  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
-  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
-
-permissions:
-  contents: read
-
-jobs:
-  checks:
-    permissions:
-      contents: write  # for Git to git push
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b # v3.2.0
-      - name: Check if C-sources are US-ASCII
-        run: |
-          ! grep -r -n '[^	 -~]' -- *.[chy] include internal win32/*.[ch]
-      - name: Check for trailing spaces
-        run: |
-          ! git grep -n '[	 ]$' -- '*.rb' '*.[chy]'
-          ! git grep -n '^[	 ][	 ]*$' -- '*.md'
-      - name: Check for bash specific substitution in configure.ac
-        run: |
-          ! git grep -n '\${[A-Za-z_0-9]*/' -- configure.ac
-      - name: Check for header macros
-        run: |
-          ! for header in ruby/*.h; do \
-            git grep -l -F -e $header -e HAVE_`echo $header | tr a-z./ A-Z__` -- . > /dev/null || echo $header
-          done | grep -F .
-        working-directory: include
-
-      - uses: actions/cache@c17f4bf4666a8001b1a45c09eb7a485c41aa64c3 # v3.2.0
-        with:
-          path: .downloaded-cache
-          key: downloaded-cache-${{ github.sha }}
-          restore-keys: |
-            downloaded-cache
-
-      - name: Download previous gems list
-        run: |
-          data=default_gems.json
-          mkdir -p .downloaded-cache
-          ln -s .downloaded-cache/$data .
-          curl -O -R -z ./$data https://stdgems.org/$data
-
-      - name: Make default gems list
-        run: |
-          #!ruby
-          require 'rubygems'
-          $:.unshift "lib"
-          rgver = File.foreach("lib/rubygems.rb") do |line|
-            break $1 if /^\s*VERSION\s*=\s*"([^"]+)"/ =~ line
-          end
-          gems = Dir.glob("{ext,lib}/**/*.gemspec").map do |f|
-            spec = Gem::Specification.load(f)
-            "#{spec.name} #{spec.version}"
-          end.sort
-          File.open("gems/default_gems", "w") do |f|
-            f.puts "RubyGems #{rgver}"
-            f.puts gems
-          end
-        shell: ruby --disable=gems {0}
-
-      - name: Maintain updated gems list in NEWS
-        run: |
-          #!ruby
-          require 'json'
-          news = File.read("NEWS.md")
-          prev = news[/since the \*+(\d+\.\d+\.\d+)\*+/, 1]
-          prevs = [prev, prev.sub(/\.\d+\z/, '')]
-          %W[default].each do |type|
-            last = JSON.parse(File.read("#{type}_gems.json"))['gems'].filter_map do |g|
-              v = g['versions'].values_at(*prevs).compact.first
-              g = g['gem']
-              g = 'RubyGems' if g == 'rubygems'
-              [g, v] if v
-            end.to_h
-            changed = File.foreach("gems/#{type}_gems").filter_map do |l|
-              next if l.start_with?("#")
-              g, v = l.split(" ", 3)
-              [g, v] unless last[g] == v
-            end
-            news.sub!(/^\*( +)The following #{type} gems? are updated\.\n+\K(?: \1\* .*\n)*/) do
-              mark = "#{$1} * "
-              changed.map {|g, v|"#{mark}#{g} #{v}\n"}.join("")
-            end or next
-            File.write("NEWS.md", news)
-          end
-        shell: ruby {0}
-
-      - name: Check diffs
-        id: diff
-        run: |
-          git diff --color --no-ext-diff --ignore-submodules --exit-code NEWS.md
-        continue-on-error: true
-      - name: Commit
-        run: |
-          git pull --ff-only origin ${GITHUB_REF#refs/heads/}
-          git commit --message="Update default gems list at ${GITHUB_SHA:0:30} [ci skip]" NEWS.md
-          git push origin ${GITHUB_REF#refs/heads/}
-        env:
-          EMAIL: svn-admin@ruby-lang.org
-          GIT_AUTHOR_NAME: git
-          GIT_COMMITTER_NAME: git
-        if: ${{ github.repository == 'ruby/ruby' && !startsWith(github.event_name, 'pull') && steps.diff.outcome == 'failure' }}
-
-      - uses: ruby/action-slack@b6882ea6ef8f556f9f9af9ec1220d3f1ced74acf # v3.0.0
-        with:
-          payload: |
-            {
-              "ci": "GitHub Actions",
-              "env": "${{ github.workflow }}",
-              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref_name }}"
-            }
-        env:
-          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: ${{ failure() && github.event_name == 'push' }}