Fix failing tests related to where values change to strings

Introduced in 5dc2e3531babcbdc165884d1a47cbcd13455522d.
change from blank? to empty? on obvious string values  to save extra method calls
Merge pull request #9784 from vipulnsward/change_from_blank_to_empty_on_string

Change from blank? to empty? on obvious string values  to save extra calls
Revert "Merge pull request #9784 from vipulnsward/change_from_blank_to_empty_on_string"

This reverts commit 9c4c05fc82e997b722dec4068c3aa27eaee69eb8, reversing
changes made to 4620bdcefd0c88905a005f191496df887877b8f3.

Reason: They're not completely interchangeable, since blank? will also
check for strings containing spaces.