Remove isList bits for attributes from codegen.

[bzbarsky-apple]

We're using isArray for lists elsewhere (struct fields, command
fields, etc), and attributes are already setting isArray anyway.

Problem

See above.

Change overview

See above.

Testing

Reran codegen. There are no changes in the generated code.

[github-actions]

PR #14305: Size comparison from b8049f0 to 7253d34

Full report (15 builds for cyw30739, efr32, k32w, linux, p6, qpg, telink)

platform	target	config	section	b8049f0	7253d34	change	% change
cyw30739	light	cyw930739m2evb_01	(read/write)	579910	579910	0	0.0
			.app_xip_area	484832	484832	0	0.0
			.bss	77824	77824	0	0.0
			.data	596	596	0	0.0
			.rodata	0	0	0	0.0
			.text	0	0	0	0.0
efr32	lighting-app	BRD4161A	(read only)	842596	842596	0	0.0
			(read/write)	127364	127364	0	0.0
			.bss	125464	125464	0	0.0
			.data	1900	1900	0	0.0
			.text	842588	842588	0	0.0
		BRD4161A+rpc	(read only)	829952	829952	0	0.0
			(read/write)	144024	144024	0	0.0
			.bss	142024	142024	0	0.0
			.data	2000	2000	0	0.0
			.text	829944	829944	0	0.0
	window-app	BRD4161A	(read only)	815228	815228	0	0.0
			(read/write)	126020	126020	0	0.0
			.bss	124164	124164	0	0.0
			.data	1856	1856	0	0.0
			.text	815220	815220	0	0.0
k32w	light	k32w061+release	(read/write)	664700	664700	0	0.0
			.bss	77596	77596	0	0.0
			.data	1868	1868	0	0.0
			.text	579436	579436	0	0.0
	lock	k32w061+release	(read/write)	665696	665696	0	0.0
			.bss	77860	77860	0	0.0
			.data	1892	1892	0	0.0
			.text	580144	580144	0	0.0
linux	chip-tool-ipv6only	arm64	(read only)	8728948	8728948	0	0.0
			(read/write)	392273	392273	0	0.0
			.bss	56241	56241	0	0.0
			.data	1128	1128	0	0.0
			.data.rel.ro	261872	261872	0	0.0
			.dynamic	560	560	0	0.0
			.got	69280	69280	0	0.0
			.init	24	24	0	0.0
			.init_array	200	200	0	0.0
			.rodata	534444	534444	0	0.0
			.text	7352756	7352756	0	0.0
	thermostat-no-ble	arm64	(read only)	2058404	2058404	0	0.0
			(read/write)	147457	147457	0	0.0
			.bss	65857	65857	0	0.0
			.data	904	904	0	0.0
			.data.rel.ro	73624	73624	0	0.0
			.dynamic	560	560	0	0.0
			.got	4112	4112	0	0.0
			.init	24	24	0	0.0
			.init_array	320	320	0	0.0
			.rodata	131396	131396	0	0.0
			.text	1711248	1711248	0	0.0
p6	all-clusters-app	default	(read/write)	2414704	2414704	0	0.0
			.bss	117892	117892	0	0.0
			.data	2584	2584	0	0.0
			.text	1372968	1372968	0	0.0
	light-app	default	(read/write)	2338168	2338168	0	0.0
			.bss	105652	105652	0	0.0
			.data	2408	2408	0	0.0
			.text	1296432	1296432	0	0.0
	lock-app	default	(read/write)	2303720	2303720	0	0.0
			.bss	105396	105396	0	0.0
			.data	2360	2360	0	0.0
			.text	1261984	1261984	0	0.0
qpg	lighting-app	qpg6105+debug	(read only)	571540	571540	0	0.0
			(read/write)	146936	146936	0	0.0
			.bss	89808	89808	0	0.0
			.data	1060	1060	0	0.0
			.text	566220	566220	0	0.0
	lock-app	qpg6105+debug	(read only)	517724	517724	0	0.0
			(read/write)	146940	146940	0	0.0
			.bss	89280	89280	0	0.0
			.data	992	992	0	0.0
			.text	512404	512404	0	0.0
	persistent-storage-app	qpg6105+debug	(read only)	107140	107140	0	0.0
			(read/write)	146940	146940	0	0.0
			.bss	38504	38504	0	0.0
			.data	288	288	0	0.0
			.text	101820	101820	0	0.0
telink	lighting-app	tlsr9518adk80d	(read/write)	847718	847718	0	0.0
			bss	87608	87608	0	0.0
			noinit	37160	37160	0	0.0
			text	592560	592560	0	0.0

[andy31415]

fast track: cleanup, provable ok by codegen not creating deltas.