Move from-iter-instead-of-collect to pedantic

Since FromIterator will become part of the prelude, this lint being
warn by default is incongruous with the libs team position on the topic.

clippy_lints/src/lib.rs

@@ -1092,6 +1092,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(methods::CLONED_INSTEAD_OF_COPIED),
         LintId::of(methods::FILTER_MAP_NEXT),
         LintId::of(methods::FLAT_MAP_OPTION),
+        LintId::of(methods::FROM_ITER_INSTEAD_OF_COLLECT),
         LintId::of(methods::IMPLICIT_CLONE),
         LintId::of(methods::INEFFICIENT_TO_STRING),
         LintId::of(methods::MAP_FLATTEN),
@@ -1288,7 +1289,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(methods::FILTER_MAP_IDENTITY),
         LintId::of(methods::FILTER_NEXT),
         LintId::of(methods::FLAT_MAP_IDENTITY),
-        LintId::of(methods::FROM_ITER_INSTEAD_OF_COLLECT),
         LintId::of(methods::INSPECT_FOR_EACH),
         LintId::of(methods::INTO_ITER_ON_REF),
         LintId::of(methods::ITERATOR_STEP_BY_ZERO),
@@ -1504,7 +1504,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(methods::BYTES_NTH),
         LintId::of(methods::CHARS_LAST_CMP),
         LintId::of(methods::CHARS_NEXT_CMP),
-        LintId::of(methods::FROM_ITER_INSTEAD_OF_COLLECT),
         LintId::of(methods::INTO_ITER_ON_REF),
         LintId::of(methods::ITER_CLONED_COLLECT),
         LintId::of(methods::ITER_NEXT_SLICE),

clippy_lints/src/methods/mod.rs

@@ -1530,7 +1530,7 @@ declare_clippy_lint! {
     /// assert_eq!(v, vec![5, 5, 5, 5, 5]);
     /// ```
     pub FROM_ITER_INSTEAD_OF_COLLECT,
-    style,
+    pedantic,
     "use `.collect()` instead of `::from_iter()`"
 }