utilxts bugfix

issue: https://gitee.com/openharmony/arkcompiler_ets_runtime/issues/I5IJY3?from=project-issue
1. u_getDataDirectory() is not thread-safe.It should be called at most once in a process
2. buffer write overflow

Signed-off-by: lukai <lukai25@huawei.com>

util/js_base64.cpp

@@ -456,8 +456,6 @@ namespace OHOS::Util {
             inputDecode = static_cast<char*>(resultData) + byteOffset;
             CreateDecodePromise(env, inputDecode, length);
         }
-        delete[] inputString;
-        inputString = nullptr;
         return stdDecodeInfo_->promise;
     }
     void Base64::CreateDecodePromise(napi_env env, char *inputDecode, size_t length)

util/js_textdecoder.cpp

@@ -42,7 +42,6 @@ namespace OHOS::Util {
             }
         }
         label_ = i32Flag;
-        SetHwIcuDirectory();
         bool fatal =
         (i32Flag & static_cast<uint32_t>(ConverterFlags::FATAL_FLG)) ==
         static_cast<uint32_t>(ConverterFlags::FATAL_FLG);