Re-enable tests after warnings collection correction

Re-enable a couple of warning header checking tests that have been
disabled, but mistakenly without linking the issue (elastic#100163), which lead
to them being kept disabled also after the fix (elastic#103031).

x-pack/plugin/esql/qa/testFixtures/src/main/resources/ints.csv-spec

@@ -499,7 +499,7 @@ ROW deg = [90, 180, 270]
 [90, 180, 270] | [1.5707963267948966, 3.141592653589793, 4.71238898038469]
 ;
 
-warningWithFromSource-Ignore
+warningWithFromSource
 from employees | sort emp_no | limit 1 | eval x = to_long(emp_no) * 10000000 | eval y = to_int(x) > 1 | keep y;
 warning:Line 1:89: evaluation of [to_int(x)] failed, treating result as null. Only first 20 failures recorded.
 warning:Line 1:89: org.elasticsearch.xpack.ql.InvalidArgumentException: [100010000000] out of [integer] range
@@ -509,7 +509,7 @@ null
 ;
 
 // the test is also notable through having the "failing" operation in the filter, which will be part of the fragment sent to a data node
-multipleWarnings-Ignore
+multipleWarnings
 from employees | sort emp_no | eval x = to_long(emp_no) * 10000000 | where to_int(x) > 1 | keep x | limit 1;
 warning:Line 1:76: evaluation of [to_int(x)] failed, treating result as null. Only first 20 failures recorded.
 warning:Line 1:76: org.elasticsearch.xpack.ql.InvalidArgumentException: [100010000000] out of [integer] range