Test 10 migrations of gl-text-secondary -> gl-text-subtle

We have 488 instances to migrate, this issue is to migrate 10 and test to see if we can safely migrate all 488 of them

Deprecated Class	Deprecated Class Value	Replacement Class	Replacement Class Value	Instances of Deprecated Class (including tests)
gl-text-secondary	#737278 (default), #89888d (dark)	gl-text-subtle	{color.neutral.600} (default), {color.neutral.200} (dark)	488