* The `sudo/ydb910` subtest in the YDBTest repository failed with the following symptom.

  ```
  --utf8 needs a value
  ```

* This test invokes `ydbinstall.sh --from-source` to build YottaDB from source. That option uses the
  `sr_unix/ydbinstall.sh` script from the YDB repository master branch on gitlab. And before transferring
  control to that script, the current version of `sr_unix/ydbinstall.sh` strips out any parameters that
  were specified after `--utf8` in the current ydbinstall.sh invocation (this change was done as part
  of a prior `[V70000]` commit 6bbb033f).

* The YDB master version does not support `--utf8` without any additional parameters and hence issues the
  above error (as it is a pre-V7.0-000-merge version).

* To avoid this test failure, this commit adds a `default` parameter after the `--utf8` before invoking
  the YDB master ydbinstall.sh.