[DOCS] Remove line about eager loading global ordinals

Fielddata can no longer be configured to be loaded eagerly (it only accepts
`true` and `false`), so this line is a little misleading because it talks about
a procedure we can no longer do.

docs/reference/mapping/params/fielddata.asciidoc

@@ -135,8 +135,7 @@ whenever a once new segment becomes visible.
 The loading time of global ordinals depends on the number of terms in a field,
 but in general it is low, since it source field data has already been loaded.
 The memory overhead of global ordinals is a small because it is very
-efficiently compressed. Eager loading of global ordinals can move the loading
-time from the first search request, to the refresh itself.
+efficiently compressed.
 
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