Fixes for UI arch and compute-resource related test-cases.

* Reformat docstrings to make them more compact.
* Drop length arguments to `gen_*` methods. They produce 10 character long strings by default, which is fine.
* Remove generic exception and use UINoSuchElementError instead.
* Fixed arch.delete locator for architecture entity.
* And many other miscellaneous fixes.
Merge pull request #1801 from kbidarkar/fix-arch-tests

Fixes for UI arch and compute-resource related test-cases.