Make sure we don't create MTRDevice/MTRDeviceController cycles we can't break.

[bzbarsky-apple]

Fixes #25710

[github-actions]

PR #25714: Size comparison from 061f80a to 3c8c7cd

Increases (1 build for cc32xx)

platform	target	config	section	061f80a	3c8c7cd	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL	.debug_info	20245969	20245970	1	0.0

Full report (1 build for cc32xx)

platform	target	config	section	061f80a	3c8c7cd	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL		0	0	0	0.0
			(read only)	645489	645489	0	0.0
			(read/write)	203848	203848	0	0.0
			.ARM.attributes	44	44	0	0.0
			.ARM.exidx	8	8	0	0.0
			.bss	197248	197248	0	0.0
			.comment	194	194	0	0.0
			.data	1480	1480	0	0.0
			.debug_abbrev	930293	930293	0	0.0
			.debug_aranges	87384	87384	0	0.0
			.debug_frame	300248	300248	0	0.0
			.debug_info	20245969	20245970	1	0.0
			.debug_line	2660979	2660979	0	0.0
			.debug_loc	2804909	2804909	0	0.0
			.debug_ranges	283168	283168	0	0.0
			.debug_str	3026947	3026947	0	0.0
			.ramVecs	780	780	0	0.0
			.resetVecs	64	64	0	0.0
			.rodata	106009	106009	0	0.0
			.shstrtab	232	232	0	0.0
			.stab	204	204	0	0.0
			.stabstr	441	441	0	0.0
			.stack	2048	2048	0	0.0
			.strtab	380271	380271	0	0.0
			.symtab	257312	257312	0	0.0
			.text	537360	537360	0	0.0

[bzbarsky-apple]

Fast-tracking platform-specific change with platform owner review.