Fix failsafe extension when we have a device attestation delegate.

[bzbarsky-apple]

The boolean test in ExtendArmFailSafeForDeviceAttestation was backwards, so there were two failure cases:

1. If we had a delegate but FailSafeExpiryTimeoutSecs() returned NullOptional, we would skip extending the fail-safe (expected), but set failSafeSkipped to false, and so not actually make our "continue commissioning" callback.

2. If we had a delegate and FailSafeExpiryTimeoutSecs() returned a too-small value, we would also skip resetting the fail-safe, but end up setting failSafeSkipped to false, and hence again failing to make our "continue commissioning" callback.

The fix is to reverse the sense of the "do we need to call back immediately" boolean, to make it a little clearer what the logic flow is here, and then check it appropriately.

[github-actions]

PR #25787: Size comparison from 6be032d to 7596377

Increases (1 build for cc32xx)

platform	target	config	section	6be032d	7596377	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL	.debug_info	20251230	20251231	1	0.0

Full report (1 build for cc32xx)

platform	target	config	section	6be032d	7596377	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL		0	0	0	0.0
			(read only)	645825	645825	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	930286	930286	0	0.0
			.debug_aranges	87400	87400	0	0.0
			.debug_frame	300336	300336	0	0.0
			.debug_info	20251230	20251231	1	0.0
			.debug_line	2661959	2661959	0	0.0
			.debug_loc	2806733	2806733	0	0.0
			.debug_ranges	283424	283424	0	0.0
			.debug_str	3027534	3027534	0	0.0
			.ramVecs	780	780	0	0.0
			.resetVecs	64	64	0	0.0
			.rodata	105993	105993	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	380469	380469	0	0.0
			.symtab	257408	257408	0	0.0
			.text	537712	537712	0	0.0