params: cleanup old params that aren't defined (#28017)

* delete files that are not defined in the keys

* assert after create file

* remove util::remove_files_in_dir

* cleanup

* fix up test

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Co-authored-by: Adeeb Shihadeh <adeebshihadeh@gmail.com>
old-commit-hash: 10a1b8b7b172420047fab5caa84829dd510e1e38

common/util.h

@@ -81,7 +81,6 @@ std::string dir_name(std::string const& path);
 // **** file fhelpers *****
 std::string read_file(const std::string& fn);
 std::map<std::string, std::string> read_files_in_dir(const std::string& path);
-void remove_files_in_dir(const std::string& path);
 int write_file(const char* path, const void* data, size_t size, int flags = O_WRONLY, mode_t mode = 0664);
 
 FILE* safe_fopen(const char* filename, const char* mode);