[rubygems/rubygems] Fix flakies in bundler gem installer specs

After introducing the `simulate_version` setting, that's another call to
`Bundler#Settings#[]` that gets in the middle and makes these specs fail
when run in isolation.

rubygems/rubygems@722360e98e

Author: deivid-rodriguez

spec/bundler/bundler/installer/gem_installer_spec.rb

@@ -23,9 +23,7 @@
 
   context "spec_settings is build option" do
     it "invokes install method with build_args" do
-      allow(Bundler.settings).to receive(:[]).with(:bin)
-      allow(Bundler.settings).to receive(:[]).with(:inline)
-      allow(Bundler.settings).to receive(:[]).with(:forget_cli_options)
+      allow(Bundler.settings).to receive(:[])
       allow(Bundler.settings).to receive(:[]).with("build.dummy").and_return("--with-dummy-config=dummy")
       expect(spec_source).to receive(:install).with(
         spec,
@@ -37,9 +35,7 @@
 
   context "spec_settings is build option with spaces" do
     it "invokes install method with build_args" do
-      allow(Bundler.settings).to receive(:[]).with(:bin)
-      allow(Bundler.settings).to receive(:[]).with(:inline)
-      allow(Bundler.settings).to receive(:[]).with(:forget_cli_options)
+      allow(Bundler.settings).to receive(:[])
       allow(Bundler.settings).to receive(:[]).with("build.dummy").and_return("--with-dummy-config=dummy --with-another-dummy-config")
       expect(spec_source).to receive(:install).with(
         spec,