[Vis colors] Replace observability color scales with palettes generated with colorPalette() and OUI color variables

[joshuarrrr]

Observability visualizations use different quantitative color scales than all other OpenSearch Dashboard visualizations:

dashboards-observability/common/constants/colors.ts

Lines 100 to 181 in d1f5d3b

	export const DEFAULT_PALETTE = 'default';
	export const SINGLE_COLOR_PALETTE = 'singleColor';
	export const MULTI_COLOR_PALETTE = 'multicolor';
	export const COLOR_PALETTES = [
	{
	value: DEFAULT_PALETTE,
	title: 'Default',
	type: 'text',
	},
	{
	value: SINGLE_COLOR_PALETTE,
	title: 'Single color',
	type: 'text',
	},
	{
	value: MULTI_COLOR_PALETTE,
	title: 'Multicolored',
	type: 'text',
	},
	{
	value: BLUES_PALETTE.name,
	title: BLUES_PALETTE.label,
	palette: colorPalette(BLUES_PALETTE.colors, 20),
	type: 'gradient',
	},
	{
	value: REDS_PALETTE.name,
	title: REDS_PALETTE.label,
	palette: colorPalette(REDS_PALETTE.colors, 20),
	type: 'gradient',
	},
	{
	value: GREENS_PALETTE.name,
	title: GREENS_PALETTE.label,
	palette: colorPalette(GREENS_PALETTE.colors, 20),
	type: 'gradient',
	},
	{
	value: GREYS_PALETTE.name,
	title: GREYS_PALETTE.label,
	palette: colorPalette(GREYS_PALETTE.colors, 20),
	type: 'gradient',
	},
	{
	value: BLUE_RED_PALETTE.name,
	title: BLUE_RED_PALETTE.label,
	palette: colorPalette(BLUE_RED_PALETTE.colors, 20),
	type: 'gradient',
	},
	{
	value: RED_BLUE_PALETTE.name,
	title: RED_BLUE_PALETTE.label,
	palette: colorPalette(RED_BLUE_PALETTE.colors, 20, true),
	type: 'gradient',
	},
	{
	value: YELLOW_ORANGE_RED_PALETTE.name,
	title: YELLOW_ORANGE_RED_PALETTE.label,
	palette: colorPalette(YELLOW_ORANGE_RED_PALETTE.colors, 20),
	type: 'gradient',
	},
	{
	value: YELLOW_GREEN_BLUE_PALETTE.name,
	title: YELLOW_GREEN_BLUE_PALETTE.label,
	palette: colorPalette(YELLOW_GREEN_BLUE_PALETTE.colors, 20),
	type: 'gradient',
	},
	];
	export const HEX_CONTRAST_COLOR = 0xffffff;
	export const PIE_PALETTES = [
	{
	value: DEFAULT_PALETTE,
	title: 'Default',
	type: 'text',
	},
	{
	value: SINGLE_COLOR_PALETTE,
	title: 'Single Color',
	type: 'text',
	},
	];

(For visual comparison, see opensearch-project/oui#601)

Visualizations should default to the standardized color scales defined in OpenSearch Dashboards, or at least use the OUI color utility colorPalette() to generate similar scales.

For a similar mitigation, see opensearch-project/OpenSearch-Dashboards#4325

[vvavdiya]

@joshuarrrr @ps48
I would like to look into issue incase any change is pending