Creepage DRC only checks F.Cu

Description

Creepage DRC only runs on F.Cu

might be a caching issue that also generates #20048 (closed), so it could be a common cause . ( I suspect we have don't invalidate the cache, so it only runs on the first layer, and does not run on subsequent runs )

Steps to reproduce

Use this board and run DRC ( also use the rule file )

mytest.kicad_pcb mytest.kicad_dru

Project archive: mytest.zip

If I remove the tracks on F_Cu, there is no violation

KiCad Version

Application: KiCad PCB Editor x64 on x64

Version: 9.0.0-rc3, release build

Libraries:
	wxWidgets 3.2.6
	FreeType 2.13.3
	HarfBuzz 10.2.0
	FontConfig 2.15.0
	libcurl/8.11.1-DEV Schannel zlib/1.3.1

Platform: Windows 10 (build 19045), 64-bit edition, 64 bit, Little endian, wxMSW
OpenGL: Intel, Intel(R) UHD Graphics, 4.6.0 - Build 30.0.101.1122

Build Info:
	Date: Feb  8 2025 03:36:34
	wxWidgets: 3.2.6 (wchar_t,wx containers)
	Boost: 1.86.0
	OCC: 7.8.1
	Curl: 8.11.1-DEV
	ngspice: 44
	Compiler: Visual C++ 1942 without C++ ABI
	KICAD_IPC_API=ON

Locale: 
	Lang: en_GB
	Enc: UTF-8
	Num: 1,234.5
	Encoded кΩ丈: D0BACEA9E4B888 (sys), D0BACEA9E4B888 (utf8)