Use "WARNING" severity for commit message inspections by default

This is primarily useful not to "hide" typos highlighting when there are also other commit message formatting issues in the same text range.

IDEA-174690

platform/vcs-impl/src/com/intellij/vcs/commit/BaseCommitMessageInspection.java

@@ -15,7 +15,6 @@
  */
 package com.intellij.vcs.commit;
 
-import com.intellij.codeHighlighting.HighlightDisplayLevel;
 import com.intellij.codeInsight.daemon.impl.IntentionActionFilter;
 import com.intellij.codeInsight.intention.EmptyIntentionAction;
 import com.intellij.codeInsight.intention.IntentionAction;
@@ -59,12 +58,6 @@ public abstract class BaseCommitMessageInspection extends LocalInspectionTool {
     return "";
   }
 
-  @NotNull
-  @Override
-  public HighlightDisplayLevel getDefaultLevel() {
-    return HighlightDisplayLevel.ERROR;
-  }
-
   @Override
   public boolean isSuppressedFor(@NotNull PsiElement element) {
     return !isCommitMessage(element);