[MM-62517] Improve cross team search UI (#30698)

Co-authored-by: Mattermost Build <build@mattermost.com>

webapp/channels/src/components/new_search/search_box.tsx

@@ -63,7 +63,7 @@ const CloseIcon = styled.button`
 
 const SearchBoxHeader = styled.div`
     display: flex;
-    align-items: center;
+    align-items: flex-end;
     justify-content: space-between;
 `;
 

webapp/channels/src/components/new_search/select_team.tsx

@@ -89,7 +89,7 @@ const SelectTeam = (props: Props) => {
                 labels={<span>{teamName}</span>}
                 trailingElements={(teamId === props.selectedTeamId && (
                     <CheckIcon
-                        size={14}
+                        size={16}
                         color='var(--button-bg, #1c58d9)'
                     />
                 ))}
@@ -107,7 +107,7 @@ const SelectTeam = (props: Props) => {
                 type='text'
                 placeholder={intl.formatMessage({id: 'search_teams_selector.search_teams', defaultMessage: 'Search teams'})}
                 className='search-teams-selector-search'
-                inputPrefix={<SearchIcon size={12}/>}
+                inputPrefix={<SearchIcon size={18}/>}
                 value={filter}
                 onChange={onFilterChange}
             />,