YJIT: Remove a dead test for getinlinecaches

The test was added in ruby#5221 4 years ago but:

1. The insn it targets was removed in 2022 in ruby#6187
2. The YJIT API `blocks_for` seems to be dropped in 2022 when it switched
   to use Rust in ruby#5826

So this test has not been run in more than 3 years and can't be run
anymore. I think we can remove it.

Author: st0012

bootstraptest/test_yjit.rb

@@ -468,91 +468,6 @@ def getter
   end
 }
 
-assert_equal '0', %q{
-  # This is a regression test for incomplete invalidation from
-  # opt_setinlinecache. This test might be brittle, so
-  # feel free to remove it in the future if it's too annoying.
-  # This test assumes --yjit-call-threshold=2.
-  module M
-    Foo = 1
-    def foo
-      Foo
-    end
-
-    def pin_self_type_then_foo
-      _ = @foo
-      foo
-    end
-
-    def only_ints
-      1 + self
-      foo
-    end
-  end
-
-  class Integer
-    include M
-  end
-
-  class Sub
-    include M
-  end
-
-  foo_method = M.instance_method(:foo)
-
-  dbg = ->(message) do
-    return # comment this out to get printouts
-
-    $stderr.puts RubyVM::YJIT.disasm(foo_method)
-    $stderr.puts message
-  end
-
-  2.times { 42.only_ints }
-
-  dbg["There should be two versions of getinlineache"]
-
-  module M
-    remove_const(:Foo)
-  end
-
-  dbg["There should be no getinlinecaches"]
-
-  2.times do
-    42.only_ints
-  rescue NameError => err
-    _ = "caught name error #{err}"
-  end
-
-  dbg["There should be one version of getinlineache"]
-
-  2.times do
-    Sub.new.pin_self_type_then_foo
-  rescue NameError
-    _ = 'second specialization'
-  end
-
-  dbg["There should be two versions of getinlineache"]
-
-  module M
-    Foo = 1
-  end
-
-  dbg["There should still be two versions of getinlineache"]
-
-  42.only_ints
-
-  dbg["There should be no getinlinecaches"]
-
-  # Find name of the first VM instruction in M#foo.
-  insns = RubyVM::InstructionSequence.of(foo_method).to_a
-  if defined?(RubyVM::YJIT.blocks_for) && (insns.last.find { Array === _1 }&.first == :opt_getinlinecache)
-    RubyVM::YJIT.blocks_for(RubyVM::InstructionSequence.of(foo_method))
-      .filter { _1.iseq_start_index == 0 }.count
-  else
-    0 # skip the test
-  end
-}
-
 # Check that frozen objects are respected
 assert_equal 'great', %q{
   class Foo