[UII] Agent activity text is not translated

[jen-huang]

The way that the strings are currently built for text in the agent activity flyout means that they are currently not registered with i18n and won't be translated:

kibana/x-pack/plugins/fleet/public/applications/fleet/sections/agents/agent_list_page/components/agent_activity_flyout/helpers.tsx

Lines 15 to 22 in 7a51ad9

	const actionNames: {
	[key: string]: { inProgressText: string; completedText: string; cancelledText: string };
	} = {
	POLICY_REASSIGN: {
	inProgressText: 'Reassigning',
	completedText: 'assigned to a new policy',
	cancelledText: 'assignment',
	},

We probably need to manually build strings for each action type + status rather than trying to build them "from config".

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)