It doesn't look like this test has ever worked, and nobody wants to mess with that code. (#133688) (#133726)

So let's just drop it - if we ever do dare to change the conversion code, we can add
proper tests then.

(cherry picked from commit 50c3cd4f5875cc5003a4e0d725deb5b7e5b4b282)

# Conflicts:
#	muted-tests.yml
#	server/src/test/java/org/elasticsearch/index/mapper/LongFieldMapperTests.java

server/src/test/java/org/elasticsearch/index/mapper/LongFieldMapperTests.java

@@ -118,11 +118,6 @@ public class LongFieldMapperTests extends WholeNumberFieldMapperTests {
         return randomDoubleBetween(-MAX_SAFE_LONG_FOR_DOUBLE, MAX_SAFE_LONG_FOR_DOUBLE, true);
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/70585")
-    public void testFetchCoerced() throws IOException {
-        assertFetch(randomFetchTestMapper(), "field", 3.783147882954537E18, randomFetchTestFormat());
-    }
-
     protected IngestScriptSupport ingestScriptSupport() {
         return new IngestScriptSupport() {
             @Override