fix(protocol-designer): fix OffDeckDetails container flicker (#17479)

Refactors padding logic in PD `OffDeckDetails` outer container to
justify right with padding, rather than justifying center and
dynamically calculating left padding based on the presence of the
details element. This prevents flickering when hovering an added offdeck
labware

Closes RQA-3953

protocol-designer/src/pages/Designer/OffDeck/OffDeckDetails.tsx

@@ -12,6 +12,7 @@ import {
   EmptySelectorButton,
   Flex,
   JUSTIFY_CENTER,
+  JUSTIFY_FLEX_END,
   LabwareRender,
   OVERFLOW_AUTO,
   RobotWorkSpace,
@@ -59,27 +60,19 @@ export function OffDeckDetails(props: OffDeckDetailsProps): JSX.Element {
   )
   const containerWidth = tab === 'startingDeck' ? '100vw' : '75vw'
 
-  const paddingLeftWithHover =
-    hoverSlot == null
-      ? `calc((${containerWidth} - (${SPACING.spacing24}  * 2) - ${OFF_DECK_MAP_WIDTH}) / 2)`
-      : SPACING.spacing24
-  const paddingLeft = tab === 'startingDeck' ? paddingLeftWithHover : undefined
-  const padding =
-    tab === 'protocolSteps'
-      ? SPACING.spacing24
-      : `${SPACING.spacing40} ${paddingLeft}`
   const stepDetailsContainerWidth = `calc(((${containerWidth} - ${OFF_DECK_MAP_WIDTH}) / 2) - (${SPACING.spacing24}  * 3))`
+  const paddingRight = `calc((100% - ${OFF_DECK_MAP_WIDTH}) / 2)`
 
   return (
     <Flex
       backgroundColor={COLORS.white}
       borderRadius={BORDERS.borderRadius12}
       width="100%"
       height="100%"
-      padding={padding}
+      padding={`${SPACING.spacing40} ${paddingRight} ${SPACING.spacing40} 0`}
       gridGap={SPACING.spacing24}
       alignItems={ALIGN_CENTER}
-      justifyContent={JUSTIFY_CENTER}
+      justifyContent={JUSTIFY_FLEX_END}
     >
       {hoverSlot != null ? (
         <Flex width={stepDetailsContainerWidth} height="6.25rem">