Schematic editor: custom worksheet file gets copied to project directory at schematic loading.

Description

Opening schematics with custom worksheet file set in page settings creates copy of worksheet file in project directory. Is there any reason to add more garbage to project directory?

Steps to reproduce

1. Open schematic editor, go to page settings, type custom worksheet file name (gost_landscape.kicad_wks in my case).
2. Save schematics, close schematic editor
3. Notice worksheet file appears in project directory.
4. Remove worksheet file from project directory.
5. Open schematic editor, load schematics.
6. Close schematic editor - notice worksheet file is in project directory again.

KiCad Version

Application: KiCad Schematic Editor

Version: (7.0.0-rc2-243-g92a61b187f), release build

Libraries:
	wxWidgets 3.0.5
	FreeType 2.11.1
	HarfBuzz 2.7.4
	FontConfig 2.13.1

Platform: Linux Mint 21.1, 64 bit, Little endian, wxGTK, cinnamon, x11

	wxWidgets: 3.0.5 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
	Boost: 1.74.0
	OCC: 7.5.1
	Curl: 7.81.0
	ngspice: 38+
	Compiler: GCC 11.3.0 with C++ ABI 1016

Build settings:
	KICAD_SPICE=ON