Altium schematic importer should not create symbol libraries

Description

The Altium schematic importer currently creates project-local symbol libraries and a symbol library table for every sheet imported. This behavior should be removed; the symbols can be stored in the schematic sheet. The current behavior results in unwanted new files being created when simply opening a sheet to view it.

KiCad Version

Application: KiCad PCB Editor arm64 on arm64

Version: 7.0.7-3-g8451e6dcf1, release build

Libraries:
	wxWidgets 3.2.2
	FreeType 2.13.0
	HarfBuzz 7.3.0
	FontConfig 2.14.2

Platform: macOS Monterey Version 12.5.1 (Build 21G83), 64 bit, Little endian, wxMac

	wxWidgets: 3.2.2 (wchar_t,wx containers)
	Boost: 1.82.0
	OCC: 7.7.0
	Curl: 7.77.0
	ngspice: 38
	Compiler: Clang 13.0.0 with C++ ABI 1002

Build settings:
	KICAD_SPICE=ON