[Uptime] Filter bar for type should actually be for scheme (#29854)

Functionally it already filters by scheme, but the label is misleading. The distinction is a particular issue when comparing the filter to the `type` column on the monitor list. Type indicates the monitor type, whereas scheme indicates the URL type. So, items with the `https` scheme have the `http` type because that's the name of the monitor.

x-pack/plugins/uptime/public/components/functional/__tests__/__snapshots__/filter_bar.test.tsx.snap

@@ -157,7 +157,7 @@ exports[`FilterBar component renders the component without errors 1`] = `
           Object {
             "field": "monitor.type",
             "multiSelect": false,
-            "name": "Type",
+            "name": "Scheme",
             "options": Array [
               Object {
                 "value": "tcp",

x-pack/plugins/uptime/public/components/functional/filter_bar.tsx

@@ -98,8 +98,8 @@ export const FilterBar = ({
     {
       type: 'field_value_selection',
       field: 'monitor.type',
-      name: i18n.translate('xpack.uptime.filterBar.options.typeLabel', {
-        defaultMessage: 'Type',
+      name: i18n.translate('xpack.uptime.filterBar.options.schemeLabel', {
+        defaultMessage: 'Scheme',
       }),
       multiSelect: false,
       options: schemes