fix: Drowdown in HC theme no longer has extra outline

[george-cz]

Previous Behavior

In HC theme, the Dropdown trigger has unnecessary outline.

New Behavior

Default:

Focused:

Related Issue(s)

• Fixes Dropdown transparent border makes focus outline harder to see in high contrast mode #27877

[fabricteam]

Perf Analysis (@fluentui/react-northstar)

Perf tests with no regressions

Scenario	Current PR Ticks	Baseline Ticks	Ratio
TreeWith60ListItems.default	93	86	1.08:1
ListNestedPerf.default	326	304	1.07:1
AttachmentMinimalPerf.default	83	78	1.06:1
CardMinimalPerf.default	322	307	1.05:1
ChatDuplicateMessagesPerf.default	153	146	1.05:1
ChatWithPopoverPerf.default	204	195	1.05:1
ImageMinimalPerf.default	226	216	1.05:1
MenuMinimalPerf.default	498	476	1.05:1
TextMinimalPerf.default	196	186	1.05:1
FormMinimalPerf.default	223	214	1.04:1
StatusMinimalPerf.default	393	379	1.04:1
TableManyItemsPerf.default	1128	1086	1.04:1
ButtonOverridesMissPerf.default	632	614	1.03:1
ListCommonPerf.default	397	386	1.03:1
ProviderMergeThemesPerf.default	669	651	1.03:1
ProviderMinimalPerf.default	202	196	1.03:1
SegmentMinimalPerf.default	202	196	1.03:1
TextAreaMinimalPerf.default	291	282	1.03:1
GridMinimalPerf.default	190	186	1.02:1
HeaderSlotsPerf.default	460	450	1.02:1
InputMinimalPerf.default	541	530	1.02:1
MenuButtonMinimalPerf.default	954	935	1.02:1
PortalMinimalPerf.default	89	87	1.02:1
SkeletonMinimalPerf.default	196	193	1.02:1
CustomToolbarPrototype.default	1429	1402	1.02:1
VideoMinimalPerf.default	436	428	1.02:1
BoxMinimalPerf.default	191	189	1.01:1
CarouselMinimalPerf.default	257	254	1.01:1
DropdownManyItemsPerf.default	386	384	1.01:1
DropdownMinimalPerf.default	1392	1376	1.01:1
EmbedMinimalPerf.default	1728	1713	1.01:1
ListWith60ListItems.default	369	366	1.01:1
LoaderMinimalPerf.default	196	195	1.01:1
RefMinimalPerf.default	111	110	1.01:1
TreeMinimalPerf.default	476	470	1.01:1
ButtonMinimalPerf.default	83	83	1:1
ChatMinimalPerf.default	421	421	1:1
DatepickerMinimalPerf.default	3642	3634	1:1
ListMinimalPerf.default	303	303	1:1
ReactionMinimalPerf.default	212	211	1:1
SliderMinimalPerf.default	684	686	1:1
SplitButtonMinimalPerf.default	2258	2252	1:1
ButtonSlotsPerf.default	309	311	0.99:1
CheckboxMinimalPerf.default	1112	1127	0.99:1
DividerMinimalPerf.default	203	206	0.99:1
RosterPerf.default	1507	1517	0.99:1
IconMinimalPerf.default	373	376	0.99:1
DialogMinimalPerf.default	445	452	0.98:1
ItemLayoutMinimalPerf.default	701	714	0.98:1
LabelMinimalPerf.default	212	216	0.98:1
PopupMinimalPerf.default	342	350	0.98:1
TableMinimalPerf.default	232	236	0.98:1
AttachmentSlotsPerf.default	614	633	0.97:1
AvatarMinimalPerf.default	102	105	0.97:1
HeaderMinimalPerf.default	198	205	0.97:1
AnimationMinimalPerf.default	284	296	0.96:1
LayoutMinimalPerf.default	199	208	0.96:1
RadioGroupMinimalPerf.default	251	262	0.96:1
ToolbarMinimalPerf.default	518	537	0.96:1
TooltipMinimalPerf.default	1239	1287	0.96:1
AlertMinimalPerf.default	148	157	0.94:1
FlexMinimalPerf.default	151	160	0.94:1
AccordionMinimalPerf.default	78	87	0.9:1

[codesandbox-ci]

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Latest deployment of this branch, based on commit 5d12b87:

Sandbox	Source
@fluentui/react 8 starter	Configuration
@fluentui/react-components 9 starter	Configuration

[fabricteam]

📊 Bundle size report

_{🤖 This report was generated against c0214bcb7d9369db75eb842adf4253893bc0e160}

[fabricteam]

🕵 FluentUI-v0 No visual regressions between this PR and main

[george-cz]

Closing as this will be resolved with #28182