Avoid trying to autostart settings handler

[Jacalz]

Description:

An idea to hopefully fix portal settings lookups hanging for desktops that don't support the spec.

Checklist:

• Tests included.
• Lint and formatter run with no errors.
• Tests all pass.

[andydotxyz]

It didn't help for me.

The stack that seems to be the hang is:

goroutine 1 gp=0xc000006380 m=nil [chan receive, locked to thread]:
runtime.gopark(0xa69627?, 0xc0002273b0?, 0x10?, 0xbd?, 0x19c9480?)
	/usr/lib/go-1.22/src/runtime/proc.go:402 +0xce fp=0xc00029fc60 sp=0xc00029fc40 pc=0x44380e
runtime.chanrecv(0xc000308540, 0xc00029fd98, 0x1)
	/usr/lib/go-1.22/src/runtime/chan.go:583 +0x3bf fp=0xc00029fcd8 sp=0xc00029fc60 pc=0x40f61f
runtime.chanrecv1(0xc0003071a0?, 0x2?)
	/usr/lib/go-1.22/src/runtime/chan.go:442 +0x12 fp=0xc00029fd00 sp=0xc00029fcd8 pc=0x40f232
github.com/godbus/dbus/v5.(*Object).Call(...)
	/home/andy/Code/Fyne/fyne/vendor/github.com/godbus/dbus/v5/object.go:34
github.com/rymdport/portal/settings.ReadOne({0xc42f4f, 0x1a}, {0xc2e631, 0xc})
	/home/andy/Code/Fyne/fyne/vendor/github.com/rymdport/portal/settings/one.go:18 +0x1a7 fp=0xc00029fdb8 sp=0xc00029fd00 pc=0xa96f67
github.com/rymdport/portal/settings/appearance.GetColorScheme()
	/home/andy/Code/Fyne/fyne/vendor/github.com/rymdport/portal/settings/appearance/color.go:24 +0x2b fp=0xc00029fde8 sp=0xc00029fdb8 pc=0xa970ab
fyne.io/fyne/v2/app.findFreedesktopColorScheme()
	/home/andy/Code/Fyne/fyne/app/app_xdg.go:40 +0xf fp=0xc00029fdf8 sp=0xc00029fde8 pc=0xab178f
fyne.io/fyne/v2/app.watchTheme()
	/home/andy/Code/Fyne/fyne/app/app_xdg.go:120 +0x13 fp=0xc00029fe10 sp=0xc00029fdf8 pc=0xab1d53
fyne.io/fyne/v2/app.(*settings).watchSettings(0xc000000b40)
	/home/andy/Code/Fyne/fyne/app/settings_desktop.go:65 +0xaa fp=0xc00029fe48 sp=0xc00029fe10 pc=0xab580a
fyne.io/fyne/v2/app.newAppWithDriver({0xd81db8, 0xc0003015f0}, {0xc0000dc24e, 0xd})
	/home/andy/Code/Fyne/fyne/app/app.go:157 +0x2a8 fp=0xc00029fe90 sp=0xc00029fe48 pc=0xab14a8
fyne.io/fyne/v2/app.NewWithID({0xc0000dc24e, 0xd})
	/home/andy/Code/Fyne/fyne/app/app_gl.go:13 +0xe5 fp=0xc00029fed8 sp=0xc00029fe90 pc=0xab1665
fyne.io/fyne/v2/app.New()
	/home/andy/Code/Fyne/fyne/app/app.go:120 +0x30 fp=0xc00029fef8 sp=0xc00029fed8 pc=0xab10d0
main.main()
	/home/andy/Code/Fyne/fyne/cmd/hello/main.go:11 +0x17 fp=0xc00029ff50 sp=0xc00029fef8 pc=0xab8677
runtime.main()
	/usr/lib/go-1.22/src/runtime/proc.go:271 +0x29d fp=0xc00029ffe0 sp=0xc00029ff50 pc=0x4433dd
runtime.goexit({})
	/usr/lib/go-1.22/src/runtime/asm_amd64.s:1695 +0x1 fp=0xc00029ffe8 sp=0xc00029ffe0 pc=0x4761e1

(though that was patching an older version of portal - the one from Fyne v2.5.0).