fix(DetailSearch): Escape Pg's regex chars in values for "~y" operator (refs #4887)

The value for "~y" was incorrectly handled as a regexp, whereas it needs
to be treated as a plain string.
Merge pull request #1264 from eguaj/3.2-A4887

fix(DetailSearch): Escape Pg's regex chars in values for "~y" operator (fixes #4887)