[Fleet][EUI Visual refresh] Check color palettes usage and make sure that they are theme-aware

[criamico]

Context

The EUI team is introducing a new theme called "Borealis". As part of this change we need to update some colors in Fleet.
See parent issue: #199715 - it also contains the instructions to run the new theme (see section Instructions for updating and QA)

Checklist

All the color palettes should now be theme aware. Details

• Check that Fleet uses any of the following colors directly. If yes, update them to pull directly from euiTheme.colors.vis.

euiColorVis0
euiColorVis1
euiColorVis2
euiColorVis3
euiColorVis4
euiColorVis5
euiColorVis6
euiColorVis7
euiColorVis8
euiColorVis9

• Check if Fleet is using one of the existing color palette functions (https://eui.elastic.co/#/utilities/color-palettes)
  • Either ensure the color palette function is called inside a React component under the EuiProvider context and is hence connected to rerender (called on rerender or connected to a state)
  • otherwise if it’s used outside of the EuiProvider context you can use the new `EUI_VIS_COLOR_STORE.subscribe() function to listen to changes and update usages manually:

const storeId = EUI_VIS_COLOR_STORE.subscribe(
 VIS_COLOR_STORE_EVENTS.UPDATE,
 () => {
   setPalette(euiPaletteColorBlind());
 }
);

➡️ There are a few instances of palette usages to check:

1. kibana/x-pack/plugins/fleet/public/applications/fleet/sections/agents/services/agent_status.tsx

   Lines 14 to 25 in 755385a

   	const visColors = euiPaletteColorBlindBehindText();
   	const colorToHexMap = {
   	// using variables as mentioned here https://elastic.github.io/eui/#/guidelines/getting-started
   	default: euiLightVars.euiColorLightShade,
   	primary: visColors[1],
   	success: visColors[0],
   	accent: visColors[2],
   	warning: visColors[5],
   	danger: visColors[9],
   	inactive: euiLightVars.euiColorDarkShade,
   	lightest: euiLightVars.euiColorDisabled,
   	};

2. kibana/x-pack/plugins/fleet/public/applications/fleet/sections/agents/agent_list_page/components/status_bar.tsx

   Line 15 in 755385a

   const StyledEuiColorPaletteDisplay = styled(EuiColorPaletteDisplay)`

These colors are visible in the agent list table. The new green used in Borealis (visible in the healthy label in the table) is now different than the green color used in the status bar and in the filters:

Definitions of done

• When testing the changes, test them both with the "old" Amsterdam theme and with the new Borealis theme.
• Please label the PR with EUI Visual Refresh for cross-team visibility

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)