[Enhancement]: delete the codes oracle related

[hnwyllmm]

Enhancement
seekdb is forked from oceanbase which is compatibility with oracle, so there're many codes related to oracle mode which can be deleted.

For example,
in file src/share/ob_errno.h

  int ob_oracle_errno(const int oberr);
  int ob_oracle_errno_with_check(const int oberr);
  const char *ob_oracle_strerror(const int oberr);
  const char *ob_oracle_str_user_error(const int oberr);

As there're too many files have such code, we should delete them with many issues and one issue with only a few code.

Before we push a pull request, we should create a related issue.