fix(ui): Set org stats controls dropdown z-index (#28161)

static/app/utils/theme.tsx

@@ -530,6 +530,12 @@ const commonTheme = {
     hovercard: 10002,
     tooltip: 10003,
 
+    // On mobile views org stats dropdowns overlap
+    orgStats: {
+      dataCategory: 1,
+      timeRange: 2,
+    },
+
     // On mobile views issue list dropdowns overlap
     issuesList: {
       stickyHeader: 1,

static/app/views/organizationStats/index.tsx

@@ -331,6 +331,7 @@ const DropdownDataCategory = styled(DropdownControl)`
   grid-column: auto / span 1;
   justify-self: stretch;
   align-self: stretch;
+  z-index: ${p => p.theme.zIndex.orgStats.dataCategory};
 
   button {
     width: 100%;
@@ -352,6 +353,7 @@ const DropdownDataCategory = styled(DropdownControl)`
 
 const StyledPageTimeRangeSelector = styled(PageTimeRangeSelector)`
   grid-column: auto / span 1;
+  z-index: ${p => p.theme.zIndex.orgStats.timeRange};
 
   @media (min-width: ${p => p.theme.breakpoints[0]}) {
     grid-column: auto / span 2;