Fix generation of certificates without an expiration date.

[bzbarsky-apple]

Since Matter encodes "no expiration" as 0, we can't just check that notAfter >= notBefore; we have to check for the case when notAfter is "no expiration" separately.

[github-actions]

PR #26402: Size comparison from c8e453c to 254b2ec

Full report (1 build for cc32xx)

platform	target	config	section	c8e453c	254b2ec	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL		0	0	0	0.0
			(read only)	605090	605090	0	0.0
			(read/write)	204164	204164	0	0.0
			.ARM.attributes	44	44	0	0.0
			.ARM.exidx	8	8	0	0.0
			.bss	197576	197576	0	0.0
			.comment	206	206	0	0.0
			.data	1468	1468	0	0.0
			.debug_abbrev	957621	957621	0	0.0
			.debug_aranges	101136	101136	0	0.0
			.debug_frame	341512	341512	0	0.0
			.debug_info	19609756	19609756	0	0.0
			.debug_line	2666632	2666632	0	0.0
			.debug_line_str	513	513	0	0.0
			.debug_loc	33340	33340	0	0.0
			.debug_loclists	1489225	1489225	0	0.0
			.debug_ranges	4984	4984	0	0.0
			.debug_rnglists	94315	94315	0	0.0
			.debug_str	3108982	3108982	0	0.0
			.ramVecs	780	780	0	0.0
			.resetVecs	64	64	0	0.0
			.rodata	104354	104354	0	0.0
			.shstrtab	265	265	0	0.0
			.stack	2048	2048	0	0.0
			.strtab	483384	483384	0	0.0
			.symtab	287328	287328	0	0.0
			.text	498612	498612	0	0.0

[github-actions]

PR #26402: Size comparison from c8e453c to 21d1bc7

Decreases (1 build for cc32xx)

platform	target	config	section	c8e453c	21d1bc7	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL	.debug_info	19609756	19609755	-1	-0.0

Full report (1 build for cc32xx)

platform	target	config	section	c8e453c	21d1bc7	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL		0	0	0	0.0
			(read only)	605090	605090	0	0.0
			(read/write)	204164	204164	0	0.0
			.ARM.attributes	44	44	0	0.0
			.ARM.exidx	8	8	0	0.0
			.bss	197576	197576	0	0.0
			.comment	206	206	0	0.0
			.data	1468	1468	0	0.0
			.debug_abbrev	957621	957621	0	0.0
			.debug_aranges	101136	101136	0	0.0
			.debug_frame	341512	341512	0	0.0
			.debug_info	19609756	19609755	-1	-0.0
			.debug_line	2666632	2666632	0	0.0
			.debug_line_str	513	513	0	0.0
			.debug_loc	33340	33340	0	0.0
			.debug_loclists	1489225	1489225	0	0.0
			.debug_ranges	4984	4984	0	0.0
			.debug_rnglists	94315	94315	0	0.0
			.debug_str	3108982	3108982	0	0.0
			.ramVecs	780	780	0	0.0
			.resetVecs	64	64	0	0.0
			.rodata	104354	104354	0	0.0
			.shstrtab	265	265	0	0.0
			.stack	2048	2048	0	0.0
			.strtab	483384	483384	0	0.0
			.symtab	287328	287328	0	0.0
			.text	498612	498612	0	0.0

[github-actions]

PR #26402: Size comparison from a2d1596 to 103086e

Full report (1 build for cc32xx)

platform	target	config	section	a2d1596	103086e	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL		0	0	0	0.0
			(read only)	604970	604970	0	0.0
			(read/write)	204164	204164	0	0.0
			.ARM.attributes	44	44	0	0.0
			.ARM.exidx	8	8	0	0.0
			.bss	197576	197576	0	0.0
			.comment	206	206	0	0.0
			.data	1468	1468	0	0.0
			.debug_abbrev	957619	957619	0	0.0
			.debug_aranges	101032	101032	0	0.0
			.debug_frame	341244	341244	0	0.0
			.debug_info	19608094	19608094	0	0.0
			.debug_line	2666175	2666175	0	0.0
			.debug_line_str	513	513	0	0.0
			.debug_loc	33340	33340	0	0.0
			.debug_loclists	1488806	1488806	0	0.0
			.debug_ranges	4984	4984	0	0.0
			.debug_rnglists	94237	94237	0	0.0
			.debug_str	3108637	3108637	0	0.0
			.ramVecs	780	780	0	0.0
			.resetVecs	64	64	0	0.0
			.rodata	104314	104314	0	0.0
			.shstrtab	265	265	0	0.0
			.stack	2048	2048	0	0.0
			.strtab	483089	483089	0	0.0
			.symtab	287200	287200	0	0.0
			.text	498532	498532	0	0.0