fix(dropdownStyles): overflow-x hidden to remove scrollbar

[assuncaocharles]

Pull request checklist

• Addresses an existing issue: Fixes #0000
• Include a change request file using $ yarn change

Description of changes

Fix scroll appearing for small dropdown

Before:

After:

Focus areas to test

(optional)

[size-auditor]

Asset size changes

Size Auditor did not detect a change in bundle size for any component!

Baseline commit: 14683472810afeead106c8e1ce8601a2331294de (build)

[ghost]

All CLA requirements met.

[fabricteam]

Perf Analysis (@fluentui/react)

No significant results to display.

All results

Scenario	Render type	Master Ticks	PR Ticks	Iterations	Status
Avatar	mount	797	806	5000
BaseButton	mount	889	898	5000
Breadcrumb	mount	2653	2677	1000
ButtonNext	mount	546	514	5000
Checkbox	mount	1520	1571	5000
CheckboxBase	mount	1313	1316	5000
ChoiceGroup	mount	4721	4751	5000
ComboBox	mount	994	987	1000
CommandBar	mount	10236	10323	1000
ContextualMenu	mount	6453	6413	1000
DefaultButton	mount	1112	1132	5000
DetailsRow	mount	3794	3705	5000
DetailsRowFast	mount	3765	3759	5000
DetailsRowNoStyles	mount	3511	3546	5000
Dialog	mount	2186	2170	1000
DocumentCardTitle	mount	147	149	1000
Dropdown	mount	3213	3221	5000
FocusTrapZone	mount	1770	1753	5000
FocusZone	mount	1780	1855	5000
IconButton	mount	1769	1749	5000
Label	mount	335	339	5000
Layer	mount	1786	1839	5000
Link	mount	467	477	5000
MakeStyles	mount	1786	1843	50000
MenuButton	mount	1455	1465	5000
MessageBar	mount	2028	2061	5000
Nav	mount	3328	3305	1000
OverflowSet	mount	1028	1064	5000
Panel	mount	2093	2095	1000
Persona	mount	813	830	1000
Pivot	mount	1417	1414	1000
PrimaryButton	mount	1293	1293	5000
Rating	mount	7573	7572	5000
SearchBox	mount	1335	1300	5000
Shimmer	mount	2549	2562	5000
Slider	mount	1966	1972	5000
SpinButton	mount	4979	5024	5000
Spinner	mount	439	416	5000
SplitButton	mount	3158	3228	5000
Stack	mount	503	509	5000
StackWithIntrinsicChildren	mount	1494	1512	5000
StackWithTextChildren	mount	4478	4534	5000
SwatchColorPicker	mount	10220	10225	5000
Tabs	mount	1408	1393	1000
TagPicker	mount	2384	2440	5000
TeachingBubble	mount	12103	11995	5000
Text	mount	417	427	5000
TextField	mount	1336	1381	5000
ThemeProvider	mount	1195	1202	5000
ThemeProvider	virtual-rerender	608	606	5000
ThemeProviderNext	mount	7170	7140	5000
Toggle	mount	809	819	5000
buttonNative	mount	121	117	5000

Perf Analysis (@fluentui/react-northstar)

Perf tests with no regressions

Scenario	Current PR Ticks	Baseline Ticks	Ratio
TreeWith60ListItems.default	187	167	1.12:1
AlertMinimalPerf.default	282	255	1.11:1
FlexMinimalPerf.default	293	272	1.08:1
SkeletonMinimalPerf.default	373	350	1.07:1
ButtonMinimalPerf.default	171	161	1.06:1
HeaderMinimalPerf.default	374	354	1.06:1
LayoutMinimalPerf.default	374	352	1.06:1
BoxMinimalPerf.default	357	339	1.05:1
LoaderMinimalPerf.default	722	691	1.04:1
TableMinimalPerf.default	409	392	1.04:1
AccordionMinimalPerf.default	159	154	1.03:1
AnimationMinimalPerf.default	422	410	1.03:1
CarouselMinimalPerf.default	466	451	1.03:1
DividerMinimalPerf.default	367	358	1.03:1
PopupMinimalPerf.default	593	578	1.03:1
RefMinimalPerf.default	243	237	1.03:1
SegmentMinimalPerf.default	349	339	1.03:1
DatepickerMinimalPerf.default	5543	5453	1.02:1
DialogMinimalPerf.default	768	750	1.02:1
ImageMinimalPerf.default	383	375	1.02:1
MenuButtonMinimalPerf.default	1618	1581	1.02:1
TreeMinimalPerf.default	799	783	1.02:1
AttachmentSlotsPerf.default	1076	1066	1.01:1
CardMinimalPerf.default	551	544	1.01:1
DropdownManyItemsPerf.default	693	685	1.01:1
DropdownMinimalPerf.default	3150	3116	1.01:1
EmbedMinimalPerf.default	4177	4137	1.01:1
HeaderSlotsPerf.default	759	752	1.01:1
InputMinimalPerf.default	1261	1247	1.01:1
ItemLayoutMinimalPerf.default	1236	1221	1.01:1
ListWith60ListItems.default	659	652	1.01:1
ProviderMergeThemesPerf.default	1692	1683	1.01:1
IconMinimalPerf.default	636	631	1.01:1
TextMinimalPerf.default	344	340	1.01:1
CustomToolbarPrototype.default	3829	3787	1.01:1
TooltipMinimalPerf.default	990	977	1.01:1
ButtonOverridesMissPerf.default	1692	1691	1:1
ButtonSlotsPerf.default	557	558	1:1
ChatMinimalPerf.default	662	662	1:1
FormMinimalPerf.default	402	402	1:1
ListMinimalPerf.default	509	510	1:1
ListNestedPerf.default	556	554	1:1
SplitButtonMinimalPerf.default	3741	3732	1:1
TableManyItemsPerf.default	1902	1909	1:1
TextAreaMinimalPerf.default	498	499	1:1
AttachmentMinimalPerf.default	152	154	0.99:1
ChatWithPopoverPerf.default	370	372	0.99:1
CheckboxMinimalPerf.default	2764	2782	0.99:1
GridMinimalPerf.default	327	330	0.99:1
LabelMinimalPerf.default	376	380	0.99:1
RosterPerf.default	1146	1152	0.99:1
RadioGroupMinimalPerf.default	446	449	0.99:1
ToolbarMinimalPerf.default	935	949	0.99:1
ListCommonPerf.default	618	630	0.98:1
ProviderMinimalPerf.default	959	975	0.98:1
StatusMinimalPerf.default	666	678	0.98:1
MenuMinimalPerf.default	827	850	0.97:1
SliderMinimalPerf.default	1512	1551	0.97:1
AvatarMinimalPerf.default	191	198	0.96:1
ReactionMinimalPerf.default	369	384	0.96:1
PortalMinimalPerf.default	175	184	0.95:1
VideoMinimalPerf.default	602	634	0.95:1
ChatDuplicateMessagesPerf.default	280	306	0.92:1