ci: reduce valgrind suppressions

Since fixing #1952 I've wanted to revisit the valgrind suppressions to
see what's left. I'm leaving only the suppressions I see for Ruby 2.7
and 3.0 startup (iseq_peephole_optimize).

suppressions/nokogiri_ruby-2.7.supp

@@ -1,42 +1,76 @@
 {
-   https://ci.nokogiri.org/teams/nokogiri-core/pipelines/nokogiri/jobs/ruby-2.7-rc-valgrind/builds/1
-   Memcheck:Addr8
-   fun:mark_locations_array
-   fun:gc_mark_stacked_objects
-   fun:gc_mark_stacked_objects_incremental
-   fun:gc_marks_rest
-   ...
-   fun:rb_ec_cleanup
-   ...
-}
-{
-   https://ci.nokogiri.org/teams/nokogiri-core/pipelines/nokogiri/jobs/ruby-2.7-rc-valgrind/builds/1
-   Memcheck:Addr8
-   fun:mark_locations_array
-   fun:gc_marks_wb_unprotected_objects
-   fun:gc_marks_finish
-   ...
-   fun:rb_ec_cleanup
-   ...
-}
-{
-   https://ci.nokogiri.org/teams/nokogiri-core/pipelines/nokogiri/jobs/ruby-2.7-rc-valgrind/builds/3
-   Memcheck:Addr8
-   fun:mark_locations_array
-   fun:gc_mark_stacked_objects
-   fun:gc_mark_stacked_objects_all
-   fun:gc_marks_rest
-   ...
-   fun:rb_ec_cleanup
-   ...
-}
-{
-   https://ci.nokogiri.org/teams/nokogiri-core/pipelines/nokogiri/jobs/ruby-2.7-valgrind/builds/1
+   ruby 2.7 startup
    Memcheck:Addr4
    fun:iseq_peephole_optimize
    fun:iseq_optimize
-   ...
+   fun:iseq_setup_insn
+   fun:iseq_setup_insn
    fun:rb_iseq_compile_node
    fun:rb_iseq_new_with_opt
+   fun:new_child_iseq
    ...
+   # fun:iseq_compile_each0
+   # fun:iseq_compile_each0
+   # fun:rb_iseq_compile_node
+   # fun:rb_iseq_new_with_opt
+   # fun:new_child_iseq
+   # fun:iseq_compile_each0
+   # fun:iseq_compile_each0
+   # fun:rb_iseq_compile_node
+   # fun:rb_iseq_new_with_opt
+   # fun:new_child_iseq
+   # fun:iseq_compile_each0
+   # fun:iseq_compile_each0
+   # fun:rb_iseq_compile_node
+   # fun:rb_iseq_new_with_opt
+   # fun:rb_iseq_new_top
+   # fun:load_iseq_eval
+   # fun:require_internal
+   # fun:rb_require_string
+   # fun:vm_call_cfunc_with_frame
+   # fun:vm_call_cfunc
+   # fun:vm_call_method_each_type.part.410
+   # fun:vm_call_method_each_type
+   # fun:vm_call_method
+   # fun:vm_sendish
+   # fun:vm_exec_core
+   # fun:rb_vm_exec
+   # fun:load_iseq_eval
+   # fun:require_internal
+   # fun:rb_require_string
+   # fun:vm_call_cfunc_with_frame
+   # fun:vm_call_cfunc
+   # fun:vm_call_method_each_type.part.410
+   # fun:vm_call_method_each_type
+   # fun:vm_call_method
+   # fun:vm_sendish
+   # fun:vm_exec_core
+   # fun:rb_vm_exec
+   # fun:load_iseq_eval
+   # fun:require_internal
+   # fun:rb_require_string
+   # fun:vm_call_cfunc_with_frame
+   # fun:vm_call_cfunc
+   # fun:vm_call_method_each_type.part.410
+   # fun:vm_call_method_each_type
+   # fun:vm_call_method
+   # fun:vm_sendish
+   # fun:vm_exec_core
+   # fun:rb_vm_exec
+   # fun:load_iseq_eval
+   # fun:require_internal
+   # fun:rb_require_string
+   # fun:vm_call_cfunc_with_frame
+   # fun:vm_call_cfunc
+   # fun:vm_call_method_each_type.part.410
+   # fun:vm_call_method_each_type
+   # fun:vm_call_method
+   # fun:vm_sendish
+   # fun:vm_exec_core
+   # fun:rb_vm_exec
+   # fun:load_iseq_eval
+   # fun:require_internal
+   # fun:rb_require_string
+   # fun:vm_call_cfunc_with_frame
+   # fun:vm_call_cfunc
 }