[Analysis] Use llvm::erase_if (NFC) (llvm#141446)

Author: kazutakahirata

clang/unittests/Analysis/ExprMutationAnalyzerTest.cpp

@@ -86,9 +86,7 @@ mutatedBy(const SmallVectorImpl<BoundNodes> &Results, ASTUnit *AST) {
 }
 
 std::string removeSpace(std::string s) {
-  s.erase(std::remove_if(s.begin(), s.end(),
-                         [](char c) { return llvm::isSpace(c); }),
-          s.end());
+  llvm::erase_if(s, llvm::isSpace);
   return s;
 }