Move certificates from Credentials to credentials

[Damian-Nordic]

Somehow, another directory "Credentials" has been created next to the existing "credentials" and they are not the same on case-sensitive filesystems.

[github-actions]

PR #25785: Size comparison from 6be032d to 2c46508

Increases (1 build for cc32xx)

platform	target	config	section	6be032d	2c46508	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL	.debug_info	20251230	20251232	2	0.0

Full report (1 build for cc32xx)

platform	target	config	section	6be032d	2c46508	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	20251232	2	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