Cleanup irb history file in tests

This was caused by the irb spec. Note that
$HOME is set during the test setup so will
always be correct.

Library/Homebrew/test/dev-cmd/irb_spec.rb

@@ -6,19 +6,29 @@ require "cmd/shared_examples/args_parse"
 describe "brew irb" do
   it_behaves_like "parseable arguments"
 
-  it "starts an interactive Homebrew shell session", :integration_test do
-    setup_test_formula "testball"
+  describe "integration test" do
+    let(:history_file) { Pathname("#{Dir.home}/.brew_irb_history") }
 
-    irb_test = HOMEBREW_TEMP/"irb-test.rb"
-    irb_test.write <<~RUBY
-      "testball".f
-      :testball.f
-      exit
-    RUBY
+    after do
+      history_file.delete if history_file.exist?
+    end
 
-    expect { brew "irb", irb_test }
-      .to output(/Interactive Homebrew Shell/).to_stdout
-      .and not_to_output.to_stderr
-      .and be_a_success
+    it "starts an interactive Homebrew shell session", :integration_test do
+      setup_test_formula "testball"
+
+      irb_test = HOMEBREW_TEMP/"irb-test.rb"
+      irb_test.write <<~RUBY
+        "testball".f
+        :testball.f
+        exit
+      RUBY
+
+      expect { brew "irb", irb_test }
+        .to output(/Interactive Homebrew Shell/).to_stdout
+        .and not_to_output.to_stderr
+        .and be_a_success
+
+      expect(history_file).to exist
+    end
   end
 end